A temporary storage apparatus is provided with a slidable buffer which does not prevent installation of the apparatus and maintenance of equipment, has increased storing capacity for carriers without a lateral transfer mechanism in a local vehicle, stores carriers between overhead travelling vehicles and a load port, and is provided with the local vehicle travelling on a rail below the rail for the overhead travelling vehicles and a slidable buffer comprising a cell to support a carrier and a guide mechanism sliding the slidable buffer between an advanced position under the rail and a backward position laterally shifted from the rail. The guide mechanism moves between an active position laterally protruding from the rail and a retracted position allowing transfer by the overhead travelling vehicles between the load port. The rail extends along the front face of the equipment to a waiting position separated from a position over the port.