To dispense with driving of an engine even in a long-time work and operate safely and efficiently by providing a pump system driven by an external power supply in a liquid supplying vehicle.

A tank lorry constituted of an oil feeding car body 1 and a fuel transfer tank 2 is remodeled by attaching an oil feed hose 3, a pump system 4, a meter 5, and an external power supply connecting receptacle 7. A reel 6 for winding the external power supply connecting receptacle 7 is attached thereto so as to prevent it from interfering the traveling. An oil feed pipe 13 connected to the pump unit 4 is connected to the tank lorry pipe part 14. The oil feed pipe 13 may be connected to anywhere in the tank lorry pipe part 14. The oil feed pipe 13 and the pump system 4 are positioned lower than the fuel transfer tank 2 so that a check valve 15 with a spring 15, etc., is attached thereto to stop the fuel so that the weight of the fuel in the fuel transfer tank 2 is prevented from directly applying to the pump system 4.