To provide a coil device, capable of being thinned to the extent that its entire length (height) is made nearly equal to the entire length of its core.

A coil 1 of this coil device includes a coil winding portion 3, a first flange portion 5, and a second flange portion 7. The first and second flange portions 5, 7 are provided in both the end portions present in the longitudinal direction of the coil winding portion 3. A pedestal 9 has a through-hole 16, and its thickness Ha as seen between its bottom surface 8 and its top surface 14 is made smaller than the whole length Hs of the core 1. The through-hole 16 of the pedestal 9 is provided in its thickness direction. The first flange portion 5 of the core 1 is inserted into the through-hole 16 of the pedestal 9, and the core 1 is so aligned with the pedestal 9 that an end surface 17 of the first flange portion 5 and the bottom surface 8 of the pedestal 9 constitute nearly the same plane to each other.