A coil component includes a first core, a second core, a lead wire, an outside mark, and an inside mark. The first core includes a winding portion and a pair of core ends. The second core connects a pair of the core ends and includes an inside surface and an outside surface. The lead wire is wound around the winding portion. The outside mark is formed on the outside surface of the second core and designed to change its arrangement at the time of rotating the second core by 90 degrees in a rotational direction whose central axis is along a normal direction of the outside surface. The inside mark with undulation is formed on the inside surface of the second core and designed to change its arrangement at the time of rotating the second core by 90 degrees in the rotational direction.