A storage compartment for loading and unloading batteries of varying sizes efficiently. The storage compartment is internally equipped with a position regulating plate part on a ceiling part, an ejection urging part, a thickness judging part, and a contact point part on an end surface at the back side. The position regulating plate part is equipped with rotatable position regulating plates urged to protrude vertically into the storage compartment. When a battery is inserted, the position regulating plates guide the battery and cause it to be pressed to a bottom surface part of the storage compartment. Any one of the position regulating plates that does not abut the battery opposes the battery in a perpendicular direction and prohibits movement of the battery in the thickness direction.