DC-DC CONVERTER DEVICE

To achieve reduction in size and reduction in cost of a DC-DC converter apparatus. Rectifier elements S1 and S2 are installed onto a metal base 10, and a drive circuit board 300 is installed to an upper part of the rectifier element. Each terminal of the rectifier elements S1 and S2 is soldered to the drive circuit board 300. Three terminals of the rectifier elements are soldered, respectively, to a drive signal wiring pattern 301, a high-potential-side main current wiring pattern 302, and a low-potential-side main current wiring pattern 303 of the board 300. A pair of output terminals of a transformer 250 is connected to at least the pair of high-potential-side main current wiring patterns 302 using high-potential-side metal conductors 402A and 402B.