A coil device includes a first coil including a plate-shaped first coil body having a first and second end. The first coil body is spirally wound on a columnar portion along the extending direction of the columnar portion such that the second end is positioned on one side in the extending direction relative to the first end. The coil device further includes a second coil including a plate-shaped second coil body having a third end and a fourth end. The second coil body is spirally wound on the columnar portion along the extending direction such that the third end is positioned on the one side in the extending direction relative to the second end of the first coil, and the fourth end is positioned on the one side in the extending direction relative to the third end. The second coil is in electrically parallel connection with the first coil.