PURPOSE: To increase the reliability for a data recording system of a disk, by adding an error correcting code to the address part of a block and adding an error detection correcting code which is common with both the data and address parts to the data part of the block to perform the recording.

CONSTITUTION: A mark 1 showing the block starting position and then an address part 2 and a data part 4 are added to a block format which performs the reading/writing on a magnetic disk. A gap 6 is secured among these mark 1 and the parts 2 and 4 respectively. An error detecting code 3 is added at the position immediately after the part 2, and at the same time an error detection correcting code 5 common with parts 2 and 4 is added at the position right after the part 4. In such way, the contents read into a buffer 12 is fed to an error detecting code circuit 13 and an error detection correcting code circuit 14 to be processed there in the reading/writing mode. As a result, a data process is possible with high reliability with a short block length.