A power converting circuit having the function of circuit detecting is provided. The power converting circuit has a transistor, a controller and a detecting circuit. The transistor receives an input voltage. The controller is coupled to a control end of the transistor to control the conducting state of the transistor so as to stabilize the output of the power converting circuit. The detecting circuit detects at least one of the control end and the low voltage end of the transistor, and generates a state signal when the detected voltage of any one of the control end and the low voltage end does not fall within a corresponding predetermined voltage range. The state signal is utilized for stopping a power circuit which provides the input voltage providing the input voltage. In addition, a light emitting diode driving circuit having the function of circuit detecting is also provided.