Abstract: A device for and method of reducing intersymbol interference (ISI) and/or crosstalk is disclosed. The ISI and crosstalk reducing device includes an optical detector which divides an optical signal reflected from an optical disk into central and peripheral parts in the tangential direction of the optical disk, and a correcting unit for controlling the gain value of a peripheral detection signal detected by the optical detector and adding the gain-controlled detection signal and a central detection signal to each other to provide an ISI corrected signal. Instead of using the existing waveform equalizer, the device uses a multiple-divided detection signal output from the optical detector to thereby obtain a jitter value of the same level as that obtained when the waveform equalizer is used. Further, in HD-DVD system requiring high density recording, it is possible to reduce crosstalk and ISI at the same time even when the high density recording causes crosstalk or interference between neighboring tracks.