PROBLEM TO BE SOLVED: To unfailingly remove a paint adhering to an area around an atomization air injection port in a spray coating system including a spray nozzle having a paint injection passage and an atomization air injection passage.SOLUTION: A spray coating system includes an atomization air passage cleaning device 30 which is connected with an atomization air supply system 3 leading to an atomization air injection passage 13 of a spray nozzle 11 through a second switching valve 31 and selectively circulates a solvent and compressed air to the atomization air injection passage 13.
