To obtain a coil device which can realize space saving, miniaturization and low cost by forming a plurality of substantially independent coils on a single core.

The coil device includes a core 6 having a middle leg 6b and having at least a pair of outer legs 6a and 6c arranged at regular intervals with the middle leg 6b, a first printed coil substrate 11 having a middle hole and a pair of outer holes for reception of the middle and outer pair legs 6b, 6a and 6c and having a first print coil 1 formed as wound around the middle hole, and a second print coil substrate 12 having the middle and outer pair holes and having a second print coil 2 of outer print coils 2a and 2b formed as wound around the outer pair holes respectively by the same turns and connected in series to generate magnetic fields in opposite directions. A voltage induced in the second print coil 2 by intersecting a magnetic flux generated by the first print coil 1 is canceled, and a magnetic flux generated by the second print coil 2 is canceled.