PURPOSE: To automatically and surely prevent the leakage of paint from a paint canister on the outer side of a spray gun.

CONSTITUTION: This spray gun and associated paint canister 7 are used to apply paint for handicrafts, model construction and similar painting or playing purposes. The paint canister has a sealing member 15 and when the paint canister exists on the outer side of the spray gun, the sealing member exists in a sealing position and covers a paint carrier range for releasing the paint by an air flow. Mutually cooperating means 10, 11, 16 and 17 are provided on the paint canister and/or the sealing member and in the interior range of the spray gun housing the paint canister. These means automatically part the sealing member from the sealing position of the paint release range of the paint carrier by inserting the paint canister into the spray gun to open the passage of the air flow passing the range and again brings the sealing member to the sealing position of the paint release range of the paint carrier when removing the paint canister from the spray gun.