An antenna coil includes an air-core coil wound helically in a plane and a plate
magnetic core member inserted in the air-core coil to be approximately parallel with a plane of the air-core coil. The
magnetic core member is formed by a soft magnetic
metal, an amorphous or ferrite, or a composite member of a
powder, flake and plastic, or rubber. The
magnetic core member is formed by performing an injection molding operation or a compressing molding operation of the composite member. Alternatively, the magnetic core member is a
magnetic coating formed by applying and
drying the composite member. A non-magnetic conductive plate that has a
conductivity is layered on a surface of the air-core coil through which the magnetic core member is inserted. The conductive plate is made of a
copper, a
copper alloy, an aluminum or an aluminum
alloy having 0.01 to 2 mm thickness. The antenna coil is operated by relatively
high frequency while it is rigid relatively.