A smart watch with an ultraviolet (UV) detector includes a base body, a display module, a UV detector module and a processor module. The base body includes a top housing and a watchband. The top housing defines a receiving chamber. At least one lateral face of the top housing is an inclined face. The inclined face is recessed inward and slantwise downward to form a groove. The display module is disposed in the receiving chamber. The UV detector module is disposed in the groove and exposed outward through the groove, wherein in use, the UV detector module is located outward and upward back to a user's body for gaining UV information. The processor module is disposed in the receiving chamber and electrically connected to the display module and the UV detector module. The processor module processes the UV information and then displays processed results on the display module.