preeq 413 a differentiator 414 for differentiating the output of the pre equalizer 413 a reproducing pll 415 for detecting synchronization when reproducing data a d converter 416 for digitizing the gain controlled signal an equalizer 417 of fdts df method or fdtrs df method a modulation code decoder 418 for decoding modulated encoded signal ecc decoder 419 for decoding the ecc encoded signal mpeg a v decoder 421 for decoding the encoded signal to mpeg format and d a converter 423 for analogously converting mpeg decoded audio video signal and outputting the converted mpeg decoded audio video signal 0055 fig4 is a block diagram showing an embodiment of equalizer 100 of the optical recording reproducing apparatus according to the present invention the equalizer 100 comprises ff unit 110 fb unit 120 a first adder 130 a slicer 140 an error calculating unit 150 a second adder 170 and a signal detection unit 160 ff unit 110 has a feedforward filter and removes pre cursor from the inter symbol interference of reproduced signal fb unit 120 has a feedback filter and predicts and outputs post cursor of the inter symbol interference based on the feedback signal from the slicer 140 in other words fb unit 120 predicts.