To provide a stick member breakage detecting device which immediately detects a breakage of stick members of various types including a pin for bearing or positioning a workpiece, when the stick members is broken for some reason.

The stick member breakage detecting device is formed of the stick member 1 (e.g. a workpiece bearing pin) having a cavity 1A therein, a pressurizing device 2 for pressurizing the interior of the cavity 1A, and a pressure detector 3 for detecting the inner pressure of the cavity 1A. According to the stick member breakage detecting device, the stick member 1 is formed such that the cavity 1A communicates with the outside upon breakage of the stick member 1, and therefore a decrease in the inner pressure of the cavity 1A is detected by the pressure detector 3, which leads to judgment as to whether the stick member is broken.