To provide a cull separating device for a semiconductor-package molding system capable of detecting a defect in a cull in the course of separating the cull, which is connected to leadframes, after molding semiconductor chips.

The cull separating device includes a lower plate 30 on which a cull 31 connected to the leadframes or the like is placed, an upper plate 32 which presses the cull of the leadframes placed on the lower plate for separating the cull from the leadframes, a pilot pin 33 which is so arranged as to penetrate the upper plate and presses the cull together with the upper plate when the upper plate presses the cull, and a sensor 34 which is arranged on the path on which the pilot pin moves and senses the movement of the pilot pin. A defective part that is not perfectly filled by molding is thereby immediately found by sensing associated with the movement of the pilot pin.