To obtain an inductor having a conductor path formed spirally on an insulator substrate in which a high Q and a high frequency are attained by providing an another conductor layer spreading sufficiently for the inductor to have distributed constants and/or a structure for suppressing self capacitance.

The spiral inductor comprises a spiral conductor path 11, and electrodes 12, 13 provided on an insulator substrate 10. Since one end of the conductor path is located in the center of the spiral, an inductor output line 14 communicating with the electrode 13 is also provided while extending above or below the spiral conductor path 11 through an insulation layer 15. It is constructed such that a conductor layer 16 is provided beneath the insulator substrate 10 and an another conductor layer 18 is provided on the inductor output line 14 through an insulation layer 17. The spiral conductor path 11 and the conductor layer 16 are provided, respectively, on the surface and rear of the insulator substrate 10 and the inductor output line 14 is provided on the conductor layer 16 through an insulation layer 19. This structure reduces the size and the cost.