Control device and brushless motor

A control device includes an obtaining unit that obtains rotation information indicating an amount of rotation and a rotation direction of a rotor of a brushless motor; and a controller that specifies a current to be provided to a coil of the brushless motor to control a rotating magnetic field generated by the coil by performing change control for gradually changing an electrical angle of the rotating magnetic field, detecting, as an initial position of the rotor, a position in which the rotor faces magnetic poles generated at an electrical angle when the rotation direction obtained during the change control changes from a first direction to a second direction and a difference between the amount of rotation in the first direction and that in the second direction obtained during the change control becomes smaller than a first threshold, and controlling the rotating magnetic field in accordance with the initial position.