A digital data recording/reproducing apparatus which divides each of information data pieces into a plurality of cells, further divides each of the cells into a series of a plurality of units, and records the units. The digital data recording/reproducing apparatus has means for recording a required time for reproduction until the head position of a unit is reached, with reference to the head position of an information data cell to which a cell belongs, as a unit start time, in addition to each of the units, and means for recording a cell start time (T.sub.s) equal to a required time for reproduction until the head position of each of the cells is reached, and a required time for reproduction (P.sub.s) of each of the cells in a management data region.