PURPOSE: To permit a player to be amused with music as a whole and permit the efficient operation of the equipment by automatically varying the degree of easiness according to the operation rate of the equipment.

CONSTITUTION: The fine setting of a program is memorized into a back-up RAM 105, and a central processing unit 101 executes the program stored in a program/data ROM 103, referring the contents. At this time, reading and writing are carried out for a variety of data RAMs 104. Accordingly, the easiness of the game is varied according to the operation rate of the equipment and stored into the data RAM 104. The data (initial set time, average cycle time) related to the easiness are determined in each play. In the initial stage, the easiness data (rank No.) at that timer are read out from the data RAM 104, and if a change is performed, the setting change for the initial set time and average cycle time is carried out according to the easiness, and the elongation time at each check point is determined, and the elongation time is shortened according to the increase of the easiness.