PURPOSE: A coating booth in which retire zone with small cross section is provided next the spray zone wherein the coater is equipped and an air-supplying duct is provided to produce an air stream only in the spray zone, thus economizing largely the power cost.

CONSTITUTION: An air controlled in humidity is blown downward through duct c straightening vanes t and air filter d to a plurality of spray zones 7 in which automatic coaters 2, 3 moving reciprocatively are equipped to form air stream A coming through grating e to cleaning zone f. Retire zone 8 with smaller cross section than that of spray zone 7 is provided next the spray zone 7 and pit 10 adjacent to cleaning zone f is sealed with floor surface 9.