A connector receptacle (20) is constituted by a contact (2) to which a data signal is serially communicated through a connector plug and a physical layer basic circuit (5) provided inside the connector receptacle (20) and adapted to perform specified processings so that the data signal is parallel communicated between the basic circuit and a link layer circuit for the communication. As a result, the distance between the contact (2) and the physical layer basic circuit (5) is short. Therefore, it is not necessary to pay so much attention as in conventional cases in designing a pattern layout (7) so as to prevent influence on the EMI and transmission characteristics, and it is easy to design the layout of the pattern constituting the transmission line for the data.