The invention provides a lid device with increased compactness and improved assembly work properties. In this lid device (20), a lid (10) that opens and closes by means of a hinge (12) is releasably locked at a closed position. The lid device is provided with: a push lifter (32) that opens/closes the lid each time the lid is pressed in; a motor (46) that is disposed in the vicinity of the push lifter; a lock member (18); and a transmission mechanism (64) that has a rack and pinion mechanism and a reduction gear train that transmit drive power from a drive means to the lock member. By means of the push lifter and drive device being disposed in a manner such that the lengthwise direction of the push lifter and the lengthwise direction of the drive device are parallel, the lid device has increased compactness and the assembly work properties are improved.