The coating apparatus comprises a body part, a head part detachably installed to this body part, and a connecting ring connecting the body part with the head part. The body part is provided with a cascade that boosts and outputs electric power and a plurality of tubes and a passage in which at least one of the optical signal, air, and coating circulates. The head part is provided with the rotary atomization head, an electric power transmission line that transmits the electric power output from the cascade, and a passage. On the connecting face of the body part, at least part of the cascade projects, and third port of the passage is exposed. On the connecting face of the head part, the electric power transmission line is connected, and a cascade insertion part in which the projected part of the cascade is inserted is formed, and a fourth port connected to the third port.