Casio

Who are Casio?

Casio is a Japanese electronics company based in Tokyo. It was founded in 1946 and began making watches in 1974, and watches are now its largest business (Casio; Wikipedia). This page covers its watch history, collections and ownership, then what to check when buying a second-hand Casio in the UK.

Casio’s watches are quartz, digital and analogue, and many are solar-powered or set themselves by radio signal or smartphone. Its most widely known range is G-Shock, launched in 1983, of which Casio reports cumulative shipments of more than 140 million (Casio). Its other watch ranges include Baby-G, Edifice, Oceanus and Pro Trek, as well as watches sold simply as Casio (Wikipedia).

The history of Casio watches

Casio’s watch history runs from a digital watch in 1974 to a range led by G-Shock. The key dates are the Casiotron (1974), the first G-Shock (1983), the F-91W (1989), Edifice (2000) and Oceanus (2004).

Before watches. Tadao Kashio founded Kashio Seisakujo, a small subcontractor, in Mitaka, Tokyo, in April 1946. Casio Computer Co., Ltd. was set up in June 1957 to make relay calculators, and its 14-A went on sale that month (Casio). Casio’s history page covers calculators; it does not cover watches.

The Casiotron. Casio entered the watch market in November 1974 with the Casiotron QW02, a digital watch with a calendar that adjusted automatically for months of different lengths (Wikipedia).

G-Shock. In 1981 Casio engineer Kikuo Ibe proposed a watch that would survive being dropped (Nippon.com). Accounts of the team differ: Nippon.com describes an eight-member Project Team Tough that built more than 200 prototypes over two years, while Wikipedia says Ibe picked a team of three that built nearly 200. The aims, Wikipedia says, were a ten-year battery, water resistance to ten bar and survival of a ten-metre fall. The first G-Shock, the DW-5000C, went on sale in 1983 (Casio). Nippon.com credits a US television advertisement, in which a G-Shock is fired into a goalie’s glove, with building sales in America.

Wider ranges. The F-91W, a digital watch designed by Ryūsuke Moriai, was introduced in June 1989 (Wikipedia). G-Shock added the Frogman diver in 1993, Baby-G for women in 1994, the all-metal MR-G in 1996 and Tough Solar charging in 1998 (Wikipedia, G-Shock). Pro Trek followed in 1995 (Notebookcheck), Edifice in 2000 (aBlogtoWatch, marking its 20th anniversary in 2020) and Oceanus in 2004 (Webchronos).

Recent years. Casio sold its 100 millionth G-Shock on 1 September 2017 (Wikipedia, G-Shock). In 2023 the Japan Patent Office registered the shape of the DW-5000C as a three-dimensional trademark, which Casio says was the first time a wristwatch’s shape alone, without logos or text, was registered in Japan (Casio).

What is Casio known for?

Casio is known for G-Shock’s shock resistance, for digital watches, and for solar, radio and Bluetooth timekeeping. The details below are each sourced.

Shock resistance. Wikipedia describes ten layers protecting the original G-Shock’s quartz module, including a urethane bumper and a steel case, and a “floating module” that sits free in a urethane foam cradle (Wikipedia, G-Shock). The 5000 line, which keeps the original 1983 shape, is G-Shock’s longest-selling line (Casio).

Digital watches. Casio began with a digital watch and still makes them. The F-91W has a stopwatch, alarm and calendar, a stated accuracy of ±30 seconds a month and a battery with a stated life of seven years (Wikipedia, Casio F-91W). It is rated to 30 metres, which Wikipedia notes is suitable only for splashes and rain; see our guide to what water resistance ratings mean.

Solar, radio and Bluetooth. Tough Solar, Casio’s solar charging, came to G-Shock in 1998, and Multi-Band 6, which sets the time from radio signals, in 2008 (Wikipedia, G-Shock). Oceanus watches use radio time-setting, Tough Solar and Mobile Link, which sets the time via a smartphone over Bluetooth (Webchronos). All of these are quartz watches; our guide to mechanical and quartz watches explains the difference. Citizen, with its own Eco-Drive solar technology, and Seiko, another large Japanese watchmaker, are Casio’s closest rivals in mass-market quartz watches.

Outdoor sensors. Many Pro Trek watches, including the 2025 anniversary models, have Casio’s Triple Sensor, combining a compass, a barometer-altimeter and a thermometer (Notebookcheck).

Which Casio collections are there?

Casio’s main watch ranges are G-Shock, Baby-G, Edifice, Pro Trek and Oceanus, plus watches sold under the Casio name alone (Wikipedia). The collections table gives the year each began and a one-line description.

A few points help when you are reading listings:

• Model and module numbers. A Casio model number, such as DW-5000C or F-91W, identifies the design. The caseback also carries a module number for the movement inside; authentication guides such as Watchscanning suggest checking it against Casio’s own listing for the model.
• The same shape, many versions. Casio has sold watches with the DW-5000C shape for 40 years while changing their function and structure (Casio), so two square G-Shocks may have quite different features. Check the exact model number.
• Nicknames. Some models are better known by fans’ names. The GA-2100’s octagonal bezel led fans to call it the “CasiOak” (Wikipedia, G-Shock). Search by model number, not nickname.
• Collaborations and limited editions. Casio releases many limited and collaboration models. A modified watch sold as a collaboration infringes Casio’s trademarks, and Casio Singapore has warned that such a watch’s warranty is void (G-Central).

Who owns Casio?

Casio’s watches are made and sold by Casio Computer Co., Ltd., a company listed on the Tokyo Stock Exchange (code 6952) and based in Shibuya, Tokyo (Wikipedia). We could not find a controlling shareholder.

Watches matter more to Casio than calculators or musical instruments. Wikipedia reports that timepieces were Casio’s largest segment in the year to March 2026, with about two-thirds of its consolidated net sales; Casio’s investor pages give total net sales for that year that are consistent with this (Casio IR).

In the UK, Casio Electronics Co. Limited was incorporated on 13 March 1975. Companies House records Casio Computer Co. Limited as holding 75% or more of its shares and voting rights (Companies House).

Buying a Casio watch second-hand in the UK: what to check

Check that the watch is genuine, that the model and module numbers match, and that it works fully: every button, the light, the solar charging or battery, and any radio or Bluetooth setting. Then check its condition and who you are buying from.

1. Fakes. Counterfeit Casios are made in volume. In June 2024 raids in Kerala, India, carried out by Casio with customs officers and police, seized more than 9,000 counterfeit watches, mainly G-Shock and Edifice (Kerala Kaumudi). A Casio watch marketing manager in Mexico told Expansión in 2025 that on a genuine watch every button has its own function, whereas on some fakes two buttons do the same thing, and that on some fakes you can see where the light comes from. Our guide on how to spot a fake watch covers the wider checks.

2. Model and module. Ask for a clear photo of the caseback and check that the model and module numbers match Casio’s listing for the watch (Watchscanning).

3. Does everything work? Ask the seller to confirm that every button, mode and the light work, and that a solar watch charges. For a radio-controlled watch, the seller may not be able to test reception, so ask how it was last set.

4. Battery and water resistance. Battery models need a new battery every few years; the F-91W’s stated battery life is seven years (Wikipedia). Ask when the battery was changed and whether the seals were checked afterwards; see our guide to water resistance ratings.

5. Condition. On a G-Shock, the outer bumper and strap are separate from the module inside (Wikipedia, G-Shock), so ask about the condition of each. Ask for close-up photos; our guide to watch condition grades explains the usual terms.

6. Vintage Casios. Early digital watches and first-generation G-Shocks are collected second-hand. Check that the display has no missing segments, and ask whether any parts have been replaced.

7. Who you buy from. Many Casios are sold privately or on marketplaces. Buying from a dealer gives you more rights; see private sellers versus dealers and your consumer rights when buying online.

8. Where it fits. A Casio is a common first watch, and wearing one is a way to learn which case size, display and features you use before trading up. Our watch sizing guide explains how to judge fit from case measurements.

For the full process from setting a budget to collecting the watch, see the guide to buying a luxury watch.

Frequently asked questions

When did Casio start making watches?

In November 1974, with the Casiotron QW02 (Wikipedia).

When was the first G-Shock made?

The first G-Shock, the DW-5000C, was launched in 1983 (Casio).

Who invented the G-Shock?

Casio engineer Kikuo Ibe, who proposed the idea in 1981 and led the team that developed it (Nippon.com; Wikipedia).

Who owns Casio?

Casio Computer Co., Ltd., a company listed on the Tokyo Stock Exchange (Wikipedia).

What is the difference between G-Shock and Baby-G?

Baby-G is a G-Shock range introduced in 1994 and designed for women (Wikipedia, G-Shock).

What is Oceanus?

Casio’s metal analogue range, launched in 2004, with radio or Bluetooth time-setting and Tough Solar charging (Webchronos).

Are Casio watches waterproof?

It depends on the model. The F-91W is rated to 30 metres, suitable only for splashes and rain (Wikipedia), while G-Shocks were designed from the start for water resistance to ten bar (Wikipedia, G-Shock). Check the rating on the caseback.

How can I tell if a G-Shock is fake?

Check the model and module numbers against Casio’s listing (Watchscanning), and that every button has its own function and the light looks even (Expansión). Buy from a seller who accepts returns if a watch is not genuine.

Why is the GA-2100 called the CasiOak?

Fans gave it the nickname because its octagonal bezel resembles the Audemars Piguet Royal Oak (Wikipedia, G-Shock).

This page is general information. Watch60 is independent and has no commercial relationship with Casio.

We check the facts on this page against the sources listed, and it is correct to the best of our knowledge as of October 2026. Brands change their warranty, servicing and sales terms, so confirm them with the brand or the seller before you buy.