To continuously operate a spray gun for a long time and to improve working efficiency by covering the periphery of a gun body with a cloth made of an air-permeable nonconductive material and blowing pressurized air between the gun body and cloth.

A cylindrical cloth 11 made of an air-permeable nonconductive material is arranged between the upper ring 4 and lower ring 8 of a gun body 2 and fixed to the upper and lower rings 4 and 8 with bands 9 and 10 to cover the periphery of the gun body 2. A groove 5 is formed in the inner periphery of the upper ring 4 to form a narrow gap 6 between the upper ring and lower gun body 2. Further, a screw hole 7 reaching the groove 5 is formed, and a hose 12 is connected to supply pressurized air, and the pressurized air is introduced between the gun body 2 and cloth 11 to inflate the cloth 11. The paint grain is discharged from the texture of the cloth 11 to the outside and the suspended grain is blown away and prevented from depositing on the cloth 11. As a result, the leakage of a voltage impressed on an electrode is prevented, and coating is continued for a long time.