A music action game machine according to clai 31, wherein the operation instructing device causes the display device to display, on the screen thereof as each of said images, an indicator provided with at least one track extending in a predetermined direction, and index marks, each of which is provided for indicating operation timing of each of the operation members, in such a manner that each of the index marks moves along the track and then reaches to a fixed operation position defined in the track when the operation timing associated with each of the index marks comes.