A controller of an injection molding machine controls mold clamping of a fixed mold and a movable mold. The controller includes a servomotor drive control unit for limiting increase in driving current during driving of a mold clamping servomotor, and a moving state acquisition unit that acquires a detection signal of an encoder. The controller further includes an abnormality determination processing unit for determining that a clamping force sensor is abnormal when recognizing stoppage of movement of the movable mold during mold clamping, based on the acquired detection signal of the encoder.