A DC-DC converter includes first and second switching devices electrically connected in series between an input terminal and a ground terminal, third and fourth switching devices electrically connected in series between an output terminal and the ground terminal, an inductor, a drive circuit that drives the first switching device to turn on and off, a bootstrap capacitor circuit connected electrically to the drive circuit, and a control circuit. The control circuit is operable to turn on and off the switching devices serially connected with each other after a simultaneous-off duration for which both of the switching devices are continuously turned off. The control circuit is operable to charge the bootstrap capacitor by continuously turning on keeping the second switching device for a charging duration while continuously turning off the first switching device for a sustaining duration determined by the simultaneous-off duration and the charging duration. This DC-DC converter can reduce a current ripple even when the bootstrap capacitor is charged.