A power supply apparatus includes a magnetic component having a coil section, a conductive case body housing the magnetic component and having an opening plane facing an axial direction of the coil section, a case lid closing the opening plane, and conductive parts electrically connecting the case body and the case lid to each other at the opening plane. The conductive parts are provided so as to satisfy a positional relationship that at least one of the conductive parts is disposed at an intersection point at which a straight line making an angle within a range of 45±15 degrees with a perpendicular line drawn from a center of the coil section to a closest one of the side plate portions of the case body to the center intersects with the closest one of side plate portions when viewed from the axial direction.