During recording the inputted data are sequentially written into a memory at one transfer rate and are read out at a second, higher transfer rate for recording on a record medium. The reading of the memory is such that data in a preset first amount are successively read from the memory to always ensure a write space in the memory which has a capacity which is higher than a predetermined second amount when the amount of the inputted data stored in the memory exceeds the first amount. During playback, the recorded data are reproduced at a second transfer rate, which is higher than a first transfer rate required for outputting the reproduced data, and are written in the memory. The thus written data are successively read out of the memory as reproduced output data at the first transfer rate. The writing of the reproduced data to the memory is controlled so that a second amount of the reproduced data is written into the memory and an amount of reproduced data, not less than a first amount, is always stored in the memory when the amount of the reproduced data stored in the memory becomes not higher than the first given amount.