Device for detecting defect signal of optical recording/reproducing device and defect signal detecting method therefof

A defect signal detecting apparatus for an optical recording/reproducing apparatus that includes a maximum value detecting unit for detecting a highest amplitude among signals input during a maximum value detection period as a maximum value, a minimum value detecting unit for detecting a lowest amplitude among signals input during a minimum value detection period as a minimum value, an asymmetry detecting unit for calculating an amount delta of asymmetry by detecting a maximum value Imax_L and a minimum value Imin_L of a signal IL having a maximum periodicity among the signal input, and a maximum value Imax_S and a minimum value Imin_S of a signal IS having a minimum periodicity among the signal input, and a defect determining unit for determining whether there is a defect in the signal input, using the maximum value, the minimum value and the amount delta of asymmetry.