PURPOSE: To smoothly and efficiently suck paint sludge along with water in a pit to send out the same.

CONSTITUTION: In a paint sludge separation device equipped with a separation tank 6 receiving paint sludge containing water W to subject paint sludge S to float separation in a storage process, a collection pit 8 receiving the floated paint sludge S from the separation tank 6 along with the water W of the surface layer part in the tank 6 and a sludge sending out passage 9 sucking the paint sludge S from the collection pit 8 along with the water W in the pit 8, a revolving means revolving the water W in the collection pit 8 around a vertical axial core of the pit 8 to allow the same to flow is provided. The suction port 9a of the sludge sending out passage 9 is arranged at the position being the revolving center part of the water W in the pit and immersed in the water in the pit. As the revolving means, the inflow port to the collection pit 8 is arranged so that the water W from the inflow port flows in from the position having a circular cross-sectional shape on a plan view and near to the outer periphery in the pit in the direction along the tangential direction of the inner peripheral surface of the pit.