A comparison system is provided with a defect inspection unit, a reference pattern storage unit, a pattern comparison unit, a comparison result processing unit and an output unit. The inspection unit inspects an object processed by a processing system, such as a semiconductor wafer, and obtains the distribution pattern of defects occurring on the surface of the object. The storage unit previously stores a reference pattern indicating a characteristic configuration of a specific portion of the processing system, which comes into contact with or approaches the object. The comparison unit compares the defect distribution pattern obtained by the defect inspection unit with the reference pattern stored in the storage unit. The comparison result processing unit obtains the degree of coincidence between the two patterns based on the comparison performed by the pattern comparison unit. The output unit outputs the obtained degree of coincidence to a display or the like.