A battery stopper stops a battery from slipping from a battery compartment in a frame of a vehicle. The battery compartment has a side opening which enables the battery to be taken in and out of the battery compartment. The battery stopper includes a stopper member capable of closing the side opening so as to cross the side opening. The stopper member is pivotally supported by a pair of frame-side fixed members that are located on both sides of the side opening, thereby enabling the side opening to be opened and closed.