Provided is a method of controlling a pressure-maintaining step for an injection-molding machine capable of molding a high quality molded body, pressure control in a pressure maintaining step executed after an injection step being performed with high precision. A control method in an injection molding machine in which there are performed an injection-filling step for advancing a screw and injecting molten resin to fill a die cavity and a pressure maintaining step for retracting the screw and reducing the pressure, wherein a switch is made to the pressure maintaining step after injection filling has concluded in the injection filling step, the screw is rapidly retracted by reducing a primary pressure through pressure control in a primary pressure maintaining step which is the initial stage after the switch to the pressure maintaining step has been made, and pressure reduction is controlled so that the reduced primary pressure reaches in a short time a set pressure for a secondary pressure maintaining step performed after the primary pressure maintaining step.