A motor module includes a motor including a commutator, and an apparatus that is attached to the motor and obtains information on rotation of the motor. The apparatus includes a rotation angle calculator that calculates a rotation angle of the motor based on a voltage between terminals of the motor and an electric current flowing through the motor, a first signal generator that generates a first signal based on a ripple component included in the electric current flowing through the motor, a second signal generator that generates a second signal indicating that the motor has rotated by a predetermined angle based on the first signal and the rotation angle, and a rotation information calculator that calculates the information on the rotation of the motor based on an output from the second signal generator.