PURPOSE: To supply a coating material stably by providing a heating means for heating the liquid stored in a tank to the given temperature, a circulating path for circulating the liquid heated in the tank, a pump for transferring compressively the liquid in the circulating path, a discharge gun for discharging the forcedly transported liquid to a work and a robot for moving the discharge gun correspondingly to the shape of the work.

CONSTITUTION: When a start switch of an operation panel 36 is operated and the make contact point F is ON, a relay RY1 is excited and the make contact point RY1a of the relay RY1 is closed, and the magnetic force of relay RY1 is self-retained. Thus, a solenoid 34a of a solenoid valve 34A for driving a valve is excited. When a solenoid valve 27A of a first coating material feeding line 17A is switched over, air feeding to a piston and cylinder section 26a on the driving side of booster pumps 26 is discontinued. The piston of the booster pump 26A is moved upward by the arrangement to start the suction process to suck the coating material in a feeding piping 18A. At that time, a check valve 30 is opened to suck the coating material on the upstream side into the piston and cylinder section 26b on the driven side, while the backflow of the coating material on the downstream side is prevented by a check valve 31. The liquid temperature is prevented from lowering by the arrangement and also increase of viscous resistance of liquid can be prevented.