The housing has a guide rail protruding from the upper face of the bottom wall portion and extending towards the rear end portion. The guide rail includes a wide portion near the front end portion and a narrow portion near the rear end portion being narrower in width than the wide portion. The sliding portion has a recessed guide groove slidably engaging the guide rail. The guide groove engages the wide portion when the card-type unit is in the locked position and engages the narrow portion instead of the wide portion when the card-type unit is in the ejection position.