A portable game machine has a game-processing unit accommodated in a housing. The game-processing unit displays, on a display, at least the image of a sub-block to be struck among a plurality of stacked sub-blocks and a main-block thereon. The game-processing unit also uses, among first strike data and second strike data sequentially input from an input unit by a game player, the first strike data as information for determining a virtual displacement of a sub-block positioned at a predetermined stage among the plurality of sub-blocks, and the second strike data as a displacement of the sub-block within the virtual displacement, and determines the displacement of the sub-block based on the second strike in the game-processing unit. The game-processing unit displays, on the display, a resultant image corresponding to the state of each of the blocks which changes based on the determination result.