This smartphone (100) has a battery lid (60) attached to the smartphone main body, and a locking member (70) which is held so as to rotatable by the smartphone main body and which rotates in response to a force received from the battery lid (60) so as to engage the battery lid (60). As a result of the engaging of the battery lid (60) by the locking member (70), the battery lid (60) is locked to the smartphone main body via the locking member (70). When viewed in perspective view from the back side of the smartphone (100), it can be seen that a housing unit (43) for housing a battery pack (50) is provided upon a lower case assembly (40).