To provide an LC composite device which is equipped with an inductor and a capacitor smaller and thinner than usual and capable of carrying a current of hundreds of mA or above.

Dielectric layers and electrode layers are alternately laminated into a capacitor, and an inductor is laminated on the one side of the capacitor for the formation of an LC composite device. A plane inductor is used as the above inductor, and the plane inductor is composed of a first ferrite magnetic film coming into contact with the capacitor, a plane coil provided on the surface of the first ferrite magnetic film, and a second ferrite magnetic film formed on the plane coil and equipped with an external electrode formed on the side of the second ferrite magnetic film and electrically connected to the terminal of the plane coil and the capacitor.