PURPOSE: To make the design operation of a game machine simply and quickly by eliminating necessity for alteraing the designs of an image signal generating means, peripheral circuits, etc., even in case an electrically varying display device to be changed after designing of the image signal generating means at the design stage of a game machine.

CONSTITUTION: This game machine is of such a structure that a VDP as an image signal generating means emits analog signals, wherein an analog/digital converting circuit 101 is installed between the VDP and an LCD in case such LCD is used as an electrically varying display device, and the signal given by the VDP is fed to the LCD upon converting into a signal which suits the signal processing system of the LCD.