Abstract: A brushless DC fan motor capable of communicating with an external apparatus while simplifying the circuitry. A speed control command generator, which generates a command for controlling the rotational speed of the rotor, include a microcomputer (9a) capable of bi-directional communication with an external apparatus (1) by serial communication based on a predetermined communication protocol. The microcomputer (9a) operates the speed control command based on control conditions transmitted from the external apparatus (1) and a signal indicative of the rotational speed and/or the exciting current detected by a speed detector (13) and/or a current detector (15) incorporated in the brushless DC fan motor (1). A drive circuit (7) controls the exciting current by PWM control according to an optimal speed control command.