Disclosed is a semiconductor device that is capable of handling multiple different high-frequency contactless communication modes and that is formed by a multi-chip structure. A first semiconductor chip, which performs interface control of high-frequency contactless communication and data processing of communications data, is mounted on a wiring board; and a second semiconductor chip, which performs another data processing of the communication data, is mounted on the first semiconductor chip. In this case, transmission pads in the first semiconductor chip are arranged at positions farther from a periphery of the chip than those of receiving pads, and the second semiconductor chip is mounted by being biased on the first semiconductor chip so as to keep away the transmission pads.