Injection molding method

An injection molding method including a measuring step for measuring an amount of the molding material by storing a molding material fed into a cylinder of an injection molding apparatus in a tip of the cylinder by rotation of a screw and stopping a rotation of the screw after the screw is retracted to a measurement set position by a pressure from the stored molding material itself, wherein

• the measuring step comprises:
• setting a back pressure to be applied on the screw, to a predetermined value;
• setting a rotation speed of the screw to a constant rotation speed within a range of 50 to 300 rpm;
• and
• adjusting a feeding speed of the molding material fed into the cylinder so that a measuring time becomes twice SN seconds or more and 180 seconds or less, the SN indicating a measuring time in a normal feeding method in which the molding material is fed from an inlet port into the cylinder to fill the cylinder by self-weight of the molding material in accordance with a material feeding capacity of the rotation speed of the screw,
• whereby the measuring time is controlled irrespective of the rotation speed of the screw and the back pressure set value.