A method of recording data to and reproducing data from a recording medium. Recording medium user identification data read from a recording medium upon which are recorded main data to be recorded and reproduced and the user identification data is compared with recorder and player user identification data read from a data recorder and player for recording and reproducing the main data and the main data are recorded to and reproduced from the recording medium when the recording medium user identification data are coincident with the recorder and player user identification data.