A phase adjusting device includes: a torque acquisition unit acquiring a torque; a position acquisition unit acquiring the rotational position of the first motor; a first motor control unit rotating the first motor in a first rotational direction until the torque exceeds a threshold, and then in a second rotational direction until the torque exceeds the threshold again; a storage control unit storing, in a storage unit, a first rotational position when the first motor is rotated in the first rotational direction and the torque exceeds the threshold and a second rotational position when the first motor is rotated in the second rotational direction and the torque exceeds the threshold again; a phase position calculator calculating a third rotational position, based on the first and second rotational positions; and a second motor control unit rotating the first motor to the third rotational position.