A wearable device may include: a strap including a substantially polygonal opening and a buckle formed at one end thereof; a buckle part configured to fasten opposite ends of the strap to each other by binding the opposite ends of the strap; and a body configured to be coupled to the opening by being fitted into the opening or decoupled from the opening. The body may include a front surface and a rear surface, and a display having a substantially polygonal shape when viewed from the top on the front surface, and a biometric sensor disposed on the rear surface.