PURPOSE: To provide a sheath tube cutting jig capable of simply cutting a sheath tube without damaging an insertion tube inserted into the sheath tube.

CONSTITUTION: This sheath tube cutting jig is provided with recesses 11 capable of being coupled with a bellows-like sheath tube PO having ridge sections P2 and valley sections P1 and projections 12 having a shape matched with the valley sections P1 of the sheath tube PO. Cutting edges 13 capable of cutting the sheath tube PO coupled with the recesses 11 are provided at two positions corresponding to the ridge sections P2 of the sheath tube PO, and the cutting edges 13 are formed into the length not protruded to the axis A-A side of the sheath tube PO from the inner face of the valley sections P1 of the sheath tube PO.