a data reproducing apparatus and method for improving data detection performance by adjusting decision levels used in a data detector . the data reproducing apparatus includes an equalizer which equalizes an input digital signal , a data detector which detects data from the output of the equalizer based on decision levels , and a level decision unit which detects levels corresponding to the decision levels used in the data detector from the output of the equalizer and feeds back corrected decision levels , which adaptively vary with the output level of the equalizer , to the data detector . accordingly , the detection performance of the data detector is improved .