A battery storage device for forklifts is used in storing a battery. The battery storage device includes a vehicle frame having a battery storage room, a front support plate provided on the vehicle frame for supporting a front surface of the battery received in the battery storage room, a rear support plate provided at a rear side of the battery storage room for supporting a rear surface of the battery received in the battery storage room, the rear support plate detachably fixed to the vehicle frame in such a manner that, when detached, the rear support plate becomes movable toward or away from the front support plate in conformity with a size of the battery, and a position adjustor for position-adjustably fixing the rear support plate in one position selected from a plurality of fixing positions.