At least one of continuous disconnection, intermittent disconnection, and temporary disconnection, of wireless communication between the input device and the game apparatus is detected. Remaining battery amount data representing a remaining battery amount of the input device is obtained via the wireless communication. It is determined that the power of the input device is insufficient based on that the wireless communication is detected to be disconnected and that the obtained remaining battery amount data represents a remaining battery amount of a predetermined level or lower. When it is determined that the power is insufficient, the power insufficiency is notified.