PURPOSE: To prevent the clogging of a filter, by a method wherein the paint mist in a booth is brought into contact with a wet filter apparatus along with air conditioning air and, thereafter, the air-conditioning air is passed through the filter of a regenerable filter apparatus.

CONSTITUTION: Paint mist in a painting booth is brought into contact with recirculation water H of a wet filter apparatus 2 along with air conditioning air supplied to said painting booth to preform the primary removal of said paint mist and air conditioning air after primary removal is further continuously passed through the filter 38 of the regenerable filter apparatus 27 to perform secondary removal. By this method, the generation of painting inferiority such as color mixing or blistering is prevented and the replacement frequency of the filter is reduced.