Abstract: A wristwatch includes a watch body having a display part on an upper surface thereof and having a seating part at an outline part of the display part, and a Bluetooth headset including a sound output unit that outputs sound information received from a master terminal, having a shape corresponding to an outline part of the display part to surround the display part, seated in the seating part, and installed to be attached to and detached from the watch body, the Bluetooth headset being a slaver terminal of the master terminal that functions as a body case or a bezel of the watch body.