A planar magnetic device 1 includes a first magnetic layer 3 and a second magnetic layer 5 that are made of a mixture of a magnetic powder 7 and a resin, and a planar coil 4 disposed between the magnetic layers. When the planar coil 4 has an adjacent winding interval W between the potions 4c of the coil and the magnetic powder 7 has a maximum particle size L, planar magnetic device 1 satisfies the relationship W>L. In the planar magnetic device 1 having the above structure, fine magnetic powder that can produce a high inductance fills the spaces between the adjacent windings. Thus, the invention can achieve a high-performance planar magnetic device, such as a thin inductor.