To provide a ball plunger with a positioning flange possible to adjust the projection dimension of a ball from a plate end surface of a mold and a jig and possible to be easily and securely fitted and removed without damaging the plate.

In this ball plunger with a positioning flange, a ball plunger main body 1 is provided with a part 2 not insertable into a counter side screw when turning the ball plunger because of the thickness thereof larger than that of the screw.