An electronic device is provided and includes a housing including a first antenna, and a binding member configured to be bound to one side of the housing. The binding member includes a strap body, a coupling part formed at one end portion of the strap body and bound to one side of the housing, an expansion part expanded inward from the housing from one end portion of the strap body, and making contact with at least a portion of a rear surface of the housing when bound, a second antenna provided in the strap body, and a coupler electrically connected with the second antenna, provided in at least a portion of the extension part, the coupler being configured to transmit a signal received through the second antenna to the first antenna.