An apparatus for verifying a custom IC including a test pattern generating unit for generating a test pattern for verifying a function of the custom IC. The test pattern is output to a master IC and a test IC. The apparatus further includes a comparing unit connected to receive operation signals output from the master IC and the test IC for comparing the operation signals to see if the operation signals are agreed with each other and for generating a comparison signal based on a comparison result, a judging unit connected to receive the comparison signal for judging if there is any abnormality in the test IC and for outputting a judged signal based on a judged result, and a computer connected to receive the judged signal for displaying the judged result of the test IC.