The invention discloses a circuit testing apparatus for testing a device under testing. The circuit testing apparatus includes a logic tester and a signal-measuring module. The logic tester is coupled to the device under testing for providing a testing signal and a trigger signal, and then determining a testing result for the device under testing according to a digital measuring result. The signal-measuring module coupled to the device under testing and the logic tester, is utilized for measuring a DC signal generated by the device under testing according to the testing signal after receiving the trigger signal, and generating the digital measuring result.