To prepare for the next supply and shipping of gas containers by rapidly dealing with an empty pallet that may be present after a shipping operation is performed while the supply of gas containers is suspended.

This apparatus is capable of forward pallet conveyance in which pallets (a) are fed forward on a forward path of conveyance 1 toward a shipping part A2; the pallets (a) that have reached the shipping part A2 are lowered onto a return path of conveyance 2; the pallets (a) are then fed forward on the return path of conveyance 2 toward a standby part A1; and the pallets (a) that have reached the standby part A1 are raised onto the forward path of conveyance 1. The apparatus is also capable of reverse pallet conveyance in which the pallets (a) are fed backward on the forward path of conveyance 1 toward the standby part A1; the pallets (a) that have reached the standby part A1 are lowered onto the return path of conveyance 2; the pallets (a) are then fed backward on the return path of conveyance 2 toward the shipping part A2; and the pallets (a) that have reached the shipping part A2 are raised onto the forward path of conveyance 1.