A motor drive circuit includes: an advance angle setting correcting device having a correction reference cycle according to a reference advance angle count value, in which a correction amount is calculated as a ratio of the correction reference cycle to a cycle of a detection signal indicating a detected frequency proportional to a motor rotation speed, and in which an advance angle setting signal is obtained by multiplying the correction amount by a proportionality factor; and an advance angle setting device in which the advance angle correction value is added to the reference advance angle count value thereby outputting an advance angle setting signal, wherein a drive command signal containing a rotation speed information based on a target rotation speed is externally fed, the motor rotation speed is variably controlled in response to the drive command signal, and the detection signal is fed from a rotation speed detecting device.