To narrow an installation surface area and efficiently recover fine sludge.

This sludge separation apparatus is provided with a separation tank 4 to which a sludge S-containing grinding liquid L is supplied, a non- magnetic metal plate 5 installed in the inside of the separation tank 4 to move the sludge S to the surface side, and a magnetic conveyer installed in the rear side of the non-magnetic metal plate 5 to adsorb the sludge S by magnetic attractive force to the surface of the non-magnetic metal plate 5 and move the sludge S toward the discharge direction. The separation apparatus is further provided with a magnetization mechanism 14 for magnetizing the sludge S contained in the grinding liquid L. The magnetization mechanism 14 is provided with an electromagnet 15 comprising a magnetization coil 16 and an electric power source 17 connected to the magnetization coil 16 of the electromagnet 15. The separation apparatus is capable of magnetizing and flocculating sludge S with the electromagnet 15 by intermittently applying electric power to the magnetization coil 16 from the electric power source 17 to precipitate the sludge S on the non-magnetic metal plate 5.