A semiconductor device includes: a semiconductor chip configured to process a signal in a radio frequency band; two conductive antenna connection pins connected with two external antenna conductors, respectively; an island for the semiconductor chip to be mounted thereon; a suspending pin connected with the island; and an antenna connection conductor configured to connect the two antenna connection pins without connection with the island and the suspending pin. A series connection of one of the two external antenna conductors, one of the two antenna connection pins, the antenna connection conductor section, the other of the two antenna connection pins and the other of the two external antenna conductors in this order, functions as an antenna by connecting the series connection with the semiconductor chip.