Abstract: A electric motor control device is provided for controlling an electric motor which actuates a movable member of a machine through a transmitting mechanism. When a torque command is given as motion command signal (9) to servo device (3), servo device (3) sends input torque signal (12) corresponding to motion command signal (9) to electric motor (5), which is energized. Movable member (7) is thus moved, producing vibrations. Servo device (3) outputs input torque signal (11) equivalent to input torque signal (12), and input torque signal (11) and rotational speed signal (10) are stored in memory device (2). Analyzing device (1) analyzes the frequencies of input torque signal (11) and rotational speed signal (10) according to an FFT, and outputs analytical result (14).