A method for controlling measurement in a motor-driven in-line screw type injection molding machine using servo-motors as a measurement driving source and an injection driving source. Control is made so that all of a measured value of back pressure controlled by the measurement servo-motor, a measured value of an astern speed of a screw controlled by the injection servo-motor, and a measured rotational speed of the screw turn zero concurrently at timing when the screw reaches a measurement completion position. Thus, suck-back can be made dispensable.