A dual IC card comprising: an IC module including a contact terminal portion contacting an external machine, a connecting coil configuring a contactless terminal portion by electromagnetic coupling, and an IC chip having a contact communication function and a contactless communication function; an antenna including a coupling coil portion formed along a coil wiring path that defines an inductance and electromagnetically coupling with the connecting coil of the IC module, a main coil portion formed along a coil wiring path that defines an inductance and connected to the coupling coil portion to perform contactless communication with the external machine, and a resistance-increasing portion (51, 52, 53B) provided in a section that forms the coil wiring path of at least one of the coupling coil portion and the main coil portion to increase electrical resistance in the section; and a plate-like card body in which the antenna is arranged, wherein: in the resistance-increasing portion (51, 52, 53B); a resistance wiring portion is provided in the section, the resistance wiring portion having a line length larger than a length of a direct connection hypothetically provided to short-cut a first point and a second point that define the section, having the same cross-sectional area as that of the direct connection, and being formed of the same material as that of the direct connection; and the resistance wiring portion provided in the section has an electrical resistance higher than that of the direct connection provided in the section, characterized in that the resistance-increasing portion (51, 52, 53B) is a wiring portion having a wiring pattern of a sinusoidal wave or a superposition of a plurality of sinusoidal waves. an IC module including a contact terminal portion contacting an external machine, a connecting coil configuring a contactless terminal portion by electromagnetic coupling, and an IC chip having a contact communication function and a contactless communication function; an antenna including a coupling coil portion formed along a coil wiring path that defines an inductance and electromagnetically coupling with the connecting coil of the IC module, a main coil portion formed along a coil wiring path that defines an inductance and connected to the coupling coil portion to perform contactless communication with the external machine, and a resistance-increasing portion (51, 52, 53B) provided in a section that forms the coil wiring path of at least one of the coupling coil portion and the main coil portion to increase electrical resistance in the section; and a plate-like card body in which the antenna is arranged, wherein: in the resistance-increasing portion (51, 52, 53B); a resistance wiring portion is provided in the section, the resistance wiring portion having a line length larger than a length of a direct connection hypothetically provided to short-cut a first point and a second point that define the section, having the same cross-sectional area as that of the direct connection, and being formed of the same material as that of the direct connection; and the resistance wiring portion provided in the section has an electrical resistance higher than that of the direct connection provided in the section, characterized in that the resistance-increasing portion (51, 52, 53B) is a wiring portion having a wiring pattern of a sinusoidal wave or a superposition of a plurality of sinusoidal waves. in the resistance-increasing portion (51, 52, 53B); a resistance wiring portion is provided in the section, the resistance wiring portion having a line length larger than a length of a direct connection hypothetically provided to short-cut a first point and a second point that define the section, having the same cross-sectional area as that of the direct connection, and being formed of the same material as that of the direct connection; and the resistance wiring portion provided in the section has an electrical resistance higher than that of the direct connection provided in the section, characterized in that the resistance-increasing portion (51, 52, 53B) is a wiring portion having a wiring pattern of a sinusoidal wave or a superposition of a plurality of sinusoidal waves.