Abstract: A spray gun, including a gun body, a handle attached to the gun body, a fluid passageway, a handle switch, and a buckle. The fluid passageway is disposed in the gun body and the handle. The handle switch is movably disposed on the handle by a rivet for opening and shutting the fluid passageway. The buckle is movably disposed on the handle via a switch shaft. The spray gun employs the buckle as a locking mechanism that has fewer parts, and therefore costs are reduced and convenience, reliability, and durability improved. The spray gun can be operated with one hand only by swinging it once to open and swinging it again to close. As a result, the performance and quality of the spray gun are improved.