An electrostatic coating system includes a coating robot (1) and an electrostatic atomizer (6) attached to a polyarticular wrist portion (5) of the robot (1). The atomizer (6) includes an end plate (45), metallic connector (50) fixed to the end plate (45) in electric conduction, high voltage generator (20) and bell head (18). Electric power is supplied to the high voltage generator (20) through the connector (50). Wires (53) are connected to the connector (50) to take out high voltage leak caused by contamination like a deposition of paint on outer surfaces of the atomizer (6) through the wires 53 to control the high voltage generator (20) to lower the value of the high voltage applied to the bell head (18) of high voltage leak detected through the wires (53) is larger than a predetermined threshold value.