A drive device includes a primary-side rectifier circuit for rectifying a received alternating-current voltage, a first capacitor for smoothing the rectified voltage, a switching element coupled to a primary winding of a transformer, for converting the smoothed voltage into an alternating-current voltage by turning on and off to be supplied to the primary winding, a secondary-side rectifying-smoothing circuit for rectifying and smoothing an alternating-current voltage induced at a secondary winding of the transformer to be outputted to a load, a switching control circuit for turning on and off the switching element by supplying a drive voltage to a control electrode of the switching element, and a bias circuit for supplying a bias voltage to the control electrode of the switching element, based on a voltage induced at the primary winding.