A fan having a temperature detecting function includes a fan frame, an extension member, a temperature sensor and a restricting portion. The fan frame has an air inlet, an air outlet, and an impeller rotatably arranged between the air inlet and the air outlet. The extension member has one end adjacent to the fan frame. The temperature sensor is arranged at one of the air inlet and the air outlet via the extension member in a position where the surface of the temperature sensor is fully exposed to the ambient air. The restricting portion is arranged at the one of the air inlet or the air outlet. The restricting portion is located between the extension member and the impeller and is adapted to prevent the extension member from making contact with the impeller.