To facilitate the setting of dwell pressure in a dwelling process and to uniformize the ansotropy of molding shrinkage in the injection molding of a product while reducing the difference of shrinkage anisotropy due to the distance from the gate of a molded product.

The advance position of an injection plunger 134 at the point of time when the operator of a plunger type injection molding machine is changed over to the dwelling process from a filling process is calculated by the arithmatic means 181 of a control part 18. The dwell pressure of the dwelling process is controlled and set by the dwelling pressure control means 182 of the control part 18 so as to hold the injection plunger 134 at the calculated advance position.