An inductor includes a coil electrode section in which a first spiral electrode and a second spiral electrode are wound in substantially the same direction, lie in substantially the same plane, and are connected to each other by a connection electrode. The coil electrode section is sandwiched by the first magnetic layer and the second magnetic layer from both directions substantially perpendicular to the plane. A first protrusion electrode and a second protrusion electrode at ends of the first spiral electrode and the second spiral electrode that are opposite to the connection electrode extend in a direction substantially perpendicular to the plane, have a length at which each of the protrusion electrodes protrudes from the first magnetic layer, and define opposite end electrodes of the inductor. Arranging this low-profile inductor on a mounting circuit board achieves a low-profile DC-DC converter including a two-layer structure.