In a converter device, an N-type FET is connected in series between an input terminal and an output terminal and an N-type FET is connected between the side of the output terminal of the N-type FET.sub.1 and a ground terminal. A smoothing circuit and a comparator circuit are connected to the side of the output terminal of the circuits. The output side of the comparator circuit is connected to an H/S driver circuit controlling the N-type FET.sub.1 through an inverter and directly connected to an L/S driver circuit controlling the N-type FET.sub.2. A reference voltage correction circuit is included in the comparator circuit, and the comparator circuit outputs an appropriate switching control signal by comparing a correction reference voltage, obtained through comparison of a divider voltage in accordance with the time average value of an output voltage with a reference voltage, with the divider voltage.