A paint booth with a purifier comprising: a booth body comprising a coating chamber and a booth opening; a water tank disposed in a lower part of the booth body; a water rope formation mechanism comprising a water case disposed in an upper part of the booth body and configured to form a plurality of parallel water ropes from water falling; a pump configured to draw up water from the water tank and feed the water into the water case; a barrier member comprising a vertically extending wall portion disposed behind the water ropes; an exhaust chamber formed behind the barrier member and divided from the coating chamber by the barrier member; an exhaust mechanism configured to discharge air from the exhaust chamber; an inclined plate comprising a water receiving surface sloping forwardly down at an angle (θ) from a vertically intermediate portion of the barrier member toward a water surface of the water tank; a windshield plate comprising an upper end and a lower end and defining an air circulation section in conjunction with a rear surface of the inclined plate, the lower end contacting water in the water tank; characterized in that the plurality of parallel water ropes from water falling are formed from nozzles formed in a bottom wall of the water case and the inclined plate is disposed below the nozzles, and in that it comprises a sludge removal mechanism comprising a conveyor configured to discharge paint sludge (M') in the water tank to the outside of the water tank, and in that it further comprises: a porous ventilation section with holes (56, 56A) disposed at a lower part of the inclined plate and an intake guide member, which extends upwardly from a sidewall of the water tank, in front of the porous ventilation section, and an inflow inlet disposed between the intake guide member and the porous ventilation section and communicating with the coating chamber. a booth body comprising a coating chamber and a booth opening; a water tank disposed in a lower part of the booth body; a water rope formation mechanism comprising a water case disposed in an upper part of the booth body and configured to form a plurality of parallel water ropes from water falling; a pump configured to draw up water from the water tank and feed the water into the water case; a barrier member comprising a vertically extending wall portion disposed behind the water ropes; an exhaust chamber formed behind the barrier member and divided from the coating chamber by the barrier member; an exhaust mechanism configured to discharge air from the exhaust chamber; an inclined plate comprising a water receiving surface sloping forwardly down at an angle (θ) from a vertically intermediate portion of the barrier member toward a water surface of the water tank; a windshield plate comprising an upper end and a lower end and defining an air circulation section in conjunction with a rear surface of the inclined plate, the lower end contacting water in the water tank; characterized in that the plurality of parallel water ropes from water falling are formed from nozzles formed in a bottom wall of the water case and the inclined plate is disposed below the nozzles, and in that it comprises a sludge removal mechanism comprising a conveyor configured to discharge paint sludge (M') in the water tank to the outside of the water tank, and in that it further comprises: a porous ventilation section with holes (56, 56A) disposed at a lower part of the inclined plate and an intake guide member, which extends upwardly from a sidewall of the water tank, in front of the porous ventilation section, and an inflow inlet disposed between the intake guide member and the porous ventilation section and communicating with the coating chamber. a porous ventilation section with holes (56, 56A) disposed at a lower part of the inclined plate and an intake guide member, which extends upwardly from a sidewall of the water tank, in front of the porous ventilation section, and an inflow inlet disposed between the intake guide member and the porous ventilation section and communicating with the coating chamber.