A DC-DC converter module comprising a switching portion, an input capacitor (Ca) and an output capacitor (Cb), the switching portion including a switching element and a magnetic element, the DC-DC converter module further comprising: a magnetic substrate having a lower surface at which an input terminal, an output terminal, and a ground terminal are disposed and having an upper surface at which an upper circuit wiring is disposed, wherein the switching element is mounted on the upper circuit wiring, and the magnetic element is disposed inside the magnetic substrate, and wherein connection wiring of connecting the upper circuit wiring and at least one of the input terminal, the output terminal, and the ground terminal is constructed using at least one inner conductor passing through the inside of the magnetic substrate, characterized in that: the input capacitor (Ca) is mounted on the upper circuit wiring and disposed adjacent to an input side of the switching portion, the output capacitor (Cb) is mounted on the upper circuit wiring and disposed adjacent to an output side of the switching portion and the connection wiring of connecting the upper circuit wiring and at least another one of the input terminal, the output terminal and the ground terminal is constructed using an end face conductor extending along an end face of the magnetic substrate, not using a via formed inside the magnetic substrate, wherein an inductance of the connection wiring using the end face conductor is lower than inductance of the connection wiring using the inner conductor. a magnetic substrate having a lower surface at which an input terminal, an output terminal, and a ground terminal are disposed and having an upper surface at which an upper circuit wiring is disposed, wherein the switching element is mounted on the upper circuit wiring, and the magnetic element is disposed inside the magnetic substrate, and wherein connection wiring of connecting the upper circuit wiring and at least one of the input terminal, the output terminal, and the ground terminal is constructed using at least one inner conductor passing through the inside of the magnetic substrate, characterized in that: the input capacitor (Ca) is mounted on the upper circuit wiring and disposed adjacent to an input side of the switching portion, the output capacitor (Cb) is mounted on the upper circuit wiring and disposed adjacent to an output side of the switching portion and the connection wiring of connecting the upper circuit wiring and at least another one of the input terminal, the output terminal and the ground terminal is constructed using an end face conductor extending along an end face of the magnetic substrate, not using a via formed inside the magnetic substrate, wherein an inductance of the connection wiring using the end face conductor is lower than inductance of the connection wiring using the inner conductor. the input capacitor (Ca) is mounted on the upper circuit wiring and disposed adjacent to an input side of the switching portion, the output capacitor (Cb) is mounted on the upper circuit wiring and disposed adjacent to an output side of the switching portion and the connection wiring of connecting the upper circuit wiring and at least another one of the input terminal, the output terminal and the ground terminal is constructed using an end face conductor extending along an end face of the magnetic substrate, not using a via formed inside the magnetic substrate, wherein an inductance of the connection wiring using the end face conductor is lower than inductance of the connection wiring using the inner conductor.