A pre-drive circuit for a brushless DC single-phase motor permits a cost reduction and an easy adjustment for the control input voltage of a switching device adjacent to a power source in a wider range, especially in increasing the control input voltage. In a drive circuit having four switching devices making up an H-bridge circuit with a motor coil being sandwiched therebetween, a control voltage exceeding a power supply voltage is required to turn ON the switching devices adjacent to the power source. The pre-drive circuit changes the duty ratio of the control voltage controlling motor speed. A circuit unit for generating pulse signals for controlling the switching devices uses an inexpensive logic circuit. Drive circuits receiving step-up voltages to amplify the pulse signals for controlling the switching devices adjacent to the power source to a level exceeding the power supply voltage and supplying the amplified pulse signals to the control input terminals of the switching devices adjacent to the power source are separately configured from peripheral circuits.