PURPOSE: To eliminate release of a pin hole of a slide piece, by inserting an auxiliary elector pin butted against an ejector pin by sliding integrally with the slide piece into a pin hole of the slide piece.

CONSTITUTION: An auxiliary ejector pin 11 is inserted into a pin hole 7d of a slide piece 7 and a cylindrical auxiliary ejector pin 11 having a length corresponding to a thickness of the slide piece up to a stationary side plane 7e from a movable side plane 7b is formed. Then, it is slid along with the slide part 7 without colliding with the other part. In the elector pin 11 further, a large diameter flange part 11a is provided on a movable side plane 7b side and a colliding surface with the ejector pin 9 is widened. At the time of injection, the pin hole 7d of the slide piece 7 is closed with the auxiliary ejector pin 11, a backward movement is prevented by a core type insert mold 3 and an inflow of a material through the pin hole does not happen. Then, at the time of ejection of a molded product, the ejector pin 9 is butted against the auxiliary ejector pin 11 by slide of the slide piece and ejected. Therefore, release of the pin hole 7d is prevented.