The apparatus of detecting defects of the present invention includes: a photodetector, detecting a intensity of reflective laser beam and generating a reflective signal; a sample/hold circuit, coupling to the photodetector circuit, sampling and holding the reflective signal; a comparator, coupling to the sample/hold circuit, comparing the sampling and holding result with a default range; and a defect flag generating circuit, coupling to the comparator, generating a defect flag signal. The method of detecting defects of the present invention includes: monitoring a reflective signal (WRF signal) when recording an optical disk; determining if the static region of WRF signal is within a predetermined range; if no, the region is regarded as a defect region, and a defect flag is set.