An opening/closing control method for a window regulator, which is a method of performing opening/closing control with a pinching prevention function while determining a detection signal from a sensor based on a threshold value. The method includes setting the threshold value as a value offset from a reference value for control, and updating the reference value in correspondence to a value of the detection signal from the sensor in an initial stage of control, and each time when the value of the detection signal from the sensor continuously changes in a certain time within a range where the value of the detection signal from the sensor does not exceed the threshold value, the reference value is modified by a value corresponding to such a changed value.