a disk stores data groups of compressed picture data arranged over sectors . a 1st data indicative of a compression method and a 2nd data indicative of the presence of the gop are contained in a leading sector . data d is located at the head of the gop . the 1st and 2nd data and gop are aligned in order . the 1st data related to a 2nd gop is detected after data d of the 1st gop is reproduced to reproduce data d of the 2nd gop . data d arranged by an interval in the gop are reproduced . in a quick traverse / reverse mode , a 2nd data d next to a 1st data d already reproduced is detected from a position of the gop corresponding to a value obtained by subtracting / adding a fixed value from / to an integerfold of the interval to reproduce the 2nd data . data d scattered over sectors of a disk are reproduced . each sector has a 1st and a 2nd field . the 1st field stores signals not interleaved relative to signals of the 2nd field . a positional data of a leading sector is recorded in the 1st field . the leading sector is located in a 3rd field in which data d is recorded . the positional data is detected to reproduce the data d .