Tadao Kashio (1917–1993) was a Japanese industrialist and the primary founder of Casio Computer Co., Ltd. Born in Kochi Prefecture, he moved to Tokyo with his family in 1923 following the Great Kanto Earthquake. He began his professional life as an apprentice lathe operator at age 14, where his mechanical skill earned him the support of his employer to study at Waseda Koshu Gakko (now Waseda University).

In April 1946, Kashio established Kashio Seisakujo in Mitaka, Tokyo. Initially a small subcontracting factory manufacturing microscope parts and gears, the business achieved its first major commercial success with the yubiwa pipe—a ring-shaped cigarette holder that allowed users to smoke hands-free. The profits from this invention provided the capital for Tadao and his three younger brothers—Toshio, Kazuo, and Yukio—to venture into the development of electric calculators.

In 1957, the brothers founded Casio Computer Co., Ltd. and released the Model 14-A, the world’s first all-electric compact relay calculator. Tadao served as the company’s financial and administrative anchor, eventually assuming the presidency in 1960. Under his leadership for nearly three decades, Casio navigated the “calculator wars” of the 1970s by introducing the Casio Mini, the first personal calculator aimed at individual consumers.

While Tadao’s brother Toshio was the primary inventor, Tadao was responsible for the strategic management that allowed the brand to diversify into the horological industry. In 1974, Casio released the Casiotron, the world’s first digital watch with an automatic calendar. This was followed by the 1983 launch of the G-Shock, which redefined the market with its focus on durability.

Tadao Kashio remained president until 1988, overseeing Casio‘s evolution from a small machine shop into a global electronics giant. He died in 1993, leaving a legacy defined by a collaborative family leadership model and a commitment to accessible, innovative technology.