A semiconductor IC has a current detection resistor and a comparison circuit for comparing the voltage drop across the current detection resistor with a threshold voltage to detect a possibly large magnitude of current passing through the current detection resistor. The semiconductor IC has a current terminal for externally inputting current to the current detection resistor, a highly resistive current-limiting resistor connected between the current detection resistor and one input end of the comparison circuit, and a measurement terminal connected to the node of the input terminal of the comparison circuit and the current limiting resistor. Thus, the magnitude of the current flowing through the measurement resistor is correctly measured without being influenced by the parasitic resistances of the terminals or of the test probe used. The threshold level of detection current is regulated based on the measured level the detection current without flowing therethrough a large amount of current nor implementing any additional device.