Casio was established as Kashio Seisakujo 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 (Toshio, Kazuo and Yukio) 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). Toshio 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 and more important 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 distinguishing 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.
Casio Computer Co., Ltd. was formed in June 1957. That year, 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.
In the 1980s, its budget electronic instruments and its line of affordable home electronic musical keyboard instruments became popular. 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 Global Positioning System displays.
A number of notable digital cameras innovations have been made by Casio, including the QV-10, the first consumer digital camera with an LCD screen on the back (developed by a team led by Hiroyuki Suetaka in 1995), the first consumer three megapixel camera, the first true ultra-compact model, and the first digital camera to incorporate ceramic lens technology.