A motor driving device includes an abnormality detecting portion arranged to detect an abnormality of one of a plurality of position detection signals based on outputs from a plurality of Hall sensors arranged to detect a rotor position of a brushless DC motor, a measuring portion arranged to measure time between neighboring edges of a normal position detection signal when the abnormality detecting portion detects an abnormality, and a drive control portion arranged to control a drive signal for driving the brushless DC motor based on a latest time measurement result of the measuring portion.