A driving circuit for a single-phase-brushless motor includes a driving-signal-generating circuit to generate a driving signal for supplying, to a driving coil of the single-phase-brushless motor, first- and second-driving currents alternately with a de-energized period therebetween, an output circuit, and a zero-cross-detecting circuit. While measuring a driving cycle from a start of an energized period, during which the output circuit supplies the first- or the second-driving current to the driving coil, to a time when the zero-cross-detecting circuit detects a zero cross of an induced voltage, generated across the driving coil, during the de-energized period, the driving-signal-generating circuit determines a length of a subsequent energized period based on the measured driving cycle, when the zero-cross-detecting circuit detects the zero-cross, and the driving-signal-generating circuit determines a length of an immediately previous energized period as a length of a subsequent energized period, when the zero-cross-detecting circuit does not detect the zero-cross.