To set and change a function and/or definition of an operation switch in terms of a program by holding a housing with both hands, operating two operation means with a right and a left finger and operating concerning plural depressing points of one operation means based on a function setting program at the time of starting a game.

Four key switches 13a to 13d are arranged in four orthogonal or crossing directions to constitute an operation instruction operating device 13 and when the key switches 13a to 13d is depressed, the depression is discriminator and processed as one of upward/downward and right/left based on a function setting program processing to utilize as an operating device for a game software necessitating two groups of direction instruction operating devices. Concerning the game of maneuvering a caterpillar, e.g. the forward/ backward rotation of the left caterpillar of a tank is instructed by depressing the upper/lower pressing points and the forward/backward rotation of the right caterpillar is instructed by depressing the upper or lower key switch 13a/13d of the right device 13.