To machine-drill workpieces up reliably at desired places by fixing them reliably with their tip pressed on a stop.

This workpiece positioning device comprises a stop 2 for positioning a workpiece 1 whose tip is pressed thereon, a sensor part 3 spaced, as prescribed, from the stop 2 to detect the distance to the tip of the workpiece 1 or to determine whether the workpiece 1 is in contact with the stop 2 or not, fixing means for fixedly holding the workpiece 1 pressed on the stop 2, moving means for moving the stop 2 in the feeding direction of the workpiece 1, and lifting means 30 for moving the stop 2 vertically. The sensor part 3 consists of a magnetic flux sensor emitting magnetic flux when detecting the distance to the tip of the workpiece 1. The workpiece positioning device, when connected to a machining device 40, securely fixes the workpiece 1 with the tip pressed on the stop 2, such that the machining device 40 can drill the workpiece 1 at desired places with reliability.