Abstract: A back-mounted battery is mounted to a rear side of a palm-top video game to supply power thereto. The battery includes a pivoted portion corresponding to a disk slot provided on the palm-top video game. When the pivoted portion of the battery is pivotally turned to a backward opened position, a player could conveniently access the disk slot and change a game disk without removing the whole battery from the video game. A U-shaped holding-down member is pivotally connected to and forward extended from a top of the battery to abut on an upper front surface of the video game, and thereby firmly hold the battery to the rear side of the video game.