Casio was established in April 1946 by Tadao Kashio, an engineer specializing in fabrication technology. Kashio's first major product was the yubiwa pipe, a finger ring that would hold a cigarette, allowing the wearer to smoke the cigarette down to its nub while also leaving the wearer's hands free. Japan was impoverished immediately following World War II, so cigarettes were valuable, and the invention was a success.
After seeing the electric calculators at the first Business Show in Ginza, Tokyo in 1949, Kashio and his younger brothers used their profits from the yubiwa pipe to develop their own calculators. Most of the calculators at that time worked using gears and could be operated by hand using a crank or using a motor (see adding machine). Kashio possessed some knowledge of electronics, and set out to make a calculator using solenoids. The desk-sized calculator was finished in 1954 and was Japan's first electro-mechanical calculator. One of the central innovations of the calculator was its adoption of the 10-key number pad; at that time other calculators were using a "full keypad", which meant that each place in the number (1s, 10s, 100s, etc...) had nine keys. Another innovation was the use of a single display window instead of the three display windows (one for each argument and one for the answer) used in other calculators.
In 1957 Casio released the Model 14-A, sold for 485,000 yen, the world's first all-electric compact calculator, which was based on relay technology. 1957 also marked the establishment of Casio Computer Co. Ltd.
In the 1980s, its budget electronic instruments and home keyboards gained huge popularity. The company also became well known for the wide variety and innovation of its wristwatches. It was one of the earliest manufacturers of quartz watches, both digital and analog. It also began selling calculator watches during this time. It was one of the first manufacturers of watches that could display the time in many different time zones and of watches with temperature, atmospheric-pressure, altitude, and even GPS position displays.
A number of notable digital cameras firsts have been made by Casio, including the first consumer digital camera with an LCD screen, the first consumer 3 megapixel camera, the first true ultra-compact model, and the first digital camera to incorporate ceramic lens technology.