To provide a defect monitoring method by which the defect of a semiconductor element can be detected with accuracy.

A reference defect pattern 104 is deliberately formed in a prescribed region of a photomask used for manufacturing a semiconductor element, and reference defects are formed on a semiconductor substrate by using the photomask carrying the pattern 104. After the operating condition of defect- detecting equipment has been adjusted so that the equipment can detect the number and sizes of the reference defects with accuracy, the defects existing in the region of an integrated circuit chip in which the semiconductor element is formed are monitored, by using the defect-detecting equipment adjusted to an optimum operating condition.