A wearable device includes a nonconductive base, a metal loop, and a matching circuit. The nonconductive base substantially has a hollow structure. The metal loop is disposed on the nonconductive base, and has a feeding point and a grounding point. The metal loop has at least one notch. The grounding point of the metal loop is coupled through the matching circuit to a ground voltage. An antenna structure of the wearable device is formed by the metal loop and the matching circuit.