the spiral member 24 is rotated relatively by the rotation drive part 20 c about the fixed shaft part 23 at the bottom part 20 a the spiral member 24 is formed with an exposed region where the spaces between the turns of the band member are open to the outer circumferential side direction at the intermediate part 20 b the spiral member 24 is surrounded in a closed manner in the outer circumferential side direction by a tubular cover member 28 the rotation drive part 20 c arranges a motor 30 in a vertical posture on the top surface of the top plate 29 and transmits rotational drive force to the spiral member 24 the bottom part 20 a is immersed in the coolant 2 in that state the rotation drive part 20 c is driven to make the spiral member 24 rotate relative to the shaft part 23 due to this the oil 12 which floats and forms a surface layer in the coolant 2 is separated from the coolant 2 in the mixed liquid state and transported upward at the top end part of the intermediate part 20 b a disk shaped receptacle 21 is attached at the top surface of the disk shaped receptacle 21 there is a recessed part which receives the separated and transported oil 12 at the top surface of the receptacle 21 the liquid recovery part 22 is formed and arranged in a shape so that the shaft part 23 and spiral member 24 pass through it in the vertical direction the oil 12 which is separated by the liquid separation.