A testing integrated circuit for a semiconductor chip, having an integrated circuit, includes a selector, provided in the integrated circuit of the semiconductor chip, for selecting one of a first set of signals supplied from external portions of the semiconductor chip and a second set of signals used for measuring voltages at respective predetermined portions in an internal circuit of the semiconductor chip. The first set of signals is converted from analog to digital signals during a normal operation of the semiconductor chip. An analog-to-digital converter provided in the integrated circuit receives an analog signal output from the selector and produces a digital signal. A plurality of output pads disposed in the semiconductor chip transmits the digital signal from the analog-to-digital converter to the external portions. The output pads correspond to a bit quantity of the analog-to-digital converter.