A coil substrate includes a plurality of structural bodies, each of which comprises a first insulating layer, a wiring formed on the first insulating layer and configured to serve as a part of a spiral coil, and a second insulating layer formed on the first insulating layer and configured to cover the wiring. The plurality of structural bodies are stacked via an adhesion layer. The spiral coil is formed by series-connecting the wirings of adjacent ones of the plurality of structural bodies.