The purpose of the present invention is to provide a workpiece separation device that smoothly discharges processing waste or a workpiece without retention on a liquid surface at the upper end of a separation container. Provided is a workpiece separation device (100) in which a liquid flow is generated from bottom to top in a separation container (110) by a liquid supply means (130) supplying a liquid from a position lower than a delivery opening (121a), the liquid overflows and flows out of an outflow opening (115a) positioned on the upper part of the separation container (110) because of this liquid flow, and a workpiece (W) and processing waste (K) are separated from each other from a mixture inserted into an insertion pipe (120) and fed into the separation container (110) from the delivery opening (121a), wherein the workpiece separation device (100) is formed such that a cross-sectional area (S) for the liquid flow path in a plane view between the inside of the separation container and the outside of the insertion pipe in intervals (LB1, LB2) in the separation container (110) from the delivery opening (121a) to the outflow opening (115a) is smaller at a position of the outflow opening (115a) than at the position of the delivery opening (121a).
