Provided is a lid device, which is compact and can be installed in an efficient manner. The lid device (20) releasably locks a lid (10) provided with a hinge (12) in a closed position. The lid device is provided with a push lifter (32) that alternates between an extended state and a retracted state each time the lid is pushed, a motor (46) placed next to the push lifter, a lock member (18) and a transmission mechanism (64) for transmitting the output of the motor. The lock member and the transmission mechanism are positioned between the push lifter and a side profile of the drive unit remote from the push lifter, and the lock member is moveable in a direction substantially perpendicular to a lengthwise direction of the push lifter and a direction from the push lifter toward the drive unit.