The operator lift a mast of the folk lift from the truck and moved forward to put the pallet on the second floor of a warehouse, As an half of the pallet stick out from the storage space, folks were bending forward and the back of the pallet was supported by the folks. The operator got out of the folk lift with the parking brake on after turning off the engine, Wheel stopper was not provided. The operator went to the second floor of the storage with the guide and transported 18-litre square cans from the pallet. When 28th can was taken out, the folk lift suddenly backed with the pallet on, as a result, the pallet was removed from the folks,the pallet and cans fell to the first floor. Oil was leaked from the broken cans.