A temporary storage apparatus for temporarily storing carriers between an overhead travelling vehicle travelling along a first travelling rail and a load port of an equipment, the temporary storage apparatus comprising: a local vehicle provided with a hoist configured to raise and lower a carrier and configured to travel; a second travelling rail for the local vehicle provided below the first travelling rail for the overhead travelling vehicle and extending to an area over the load port; at least one slidable buffer configured to support a carrier thereon and to slide between a first position under the second travelling rail for the local vehicle and a second position laterally separated from the first position under the second travelling rail for the local vehicle; and a controller configured to control the local vehicle and the slidable buffer, the apparatus being characterized in that the second travelling rail for the local vehicle is configured to extend from the area over the load port to a waiting position for the local vehicle shifted from the area over the load port, wherein the local vehicle is configured to wait at said waiting position, wherein the slidable buffer comprises a base and a movable pedestal configured to move forward from the base to a position under the second travelling rail for the local vehicle, wherein said base is fixed at a position laterally separated from the first position under the second travelling rail for the local vehicle, wherein a first sensor configured to detect that the pedestal is located at the first position under the second travelling rail for the local vehicle and a second sensor configured to detect that the pedestal is located at a position over the base are provided, and wherein said controller is configured and programmed to permit the overhead travelling vehicle and the local vehicle to transfer a carrier to the slidable buffer according to a detected position of the pedestal. a local vehicle provided with a hoist configured to raise and lower a carrier and configured to travel; a second travelling rail for the local vehicle provided below the first travelling rail for the overhead travelling vehicle and extending to an area over the load port; at least one slidable buffer configured to support a carrier thereon and to slide between a first position under the second travelling rail for the local vehicle and a second position laterally separated from the first position under the second travelling rail for the local vehicle; and a controller configured to control the local vehicle and the slidable buffer, the apparatus being characterized in that the second travelling rail for the local vehicle is configured to extend from the area over the load port to a waiting position for the local vehicle shifted from the area over the load port, wherein the local vehicle is configured to wait at said waiting position, wherein the slidable buffer comprises a base and a movable pedestal configured to move forward from the base to a position under the second travelling rail for the local vehicle, wherein said base is fixed at a position laterally separated from the first position under the second travelling rail for the local vehicle, wherein a first sensor configured to detect that the pedestal is located at the first position under the second travelling rail for the local vehicle and a second sensor configured to detect that the pedestal is located at a position over the base are provided, and wherein said controller is configured and programmed to permit the overhead travelling vehicle and the local vehicle to transfer a carrier to the slidable buffer according to a detected position of the pedestal.