PURPOSE: To obtain digital modulation that can satisfy not only the conditions which are preferable in conventional modulating system but also the conditions which are ignored and is more suitable for digital magnetic recording, by converting 8-bit information words into 14-bit block codes.

CONSTITUTION: By limiting the continuation of the first and final '0' or '1' to five or less and selecting 14-bit data, in which the continuation becomes between two and ten, the 1st converted code set, composed of a converted code group which has each seven pieces of '0' and '1' and whose 1st bit is '0' and another converted code group which has each seven pieces of '0' and '1' and whose 1st bit is '1', is selected. Similarly, the 2nd and 3rd sets are selected thereafter. Then 256 pieces of converted codes are extracted from these sets and the extracted converted codes are made to correspond 8-bit information words. Thereafter, by monitoring the DSV when '0' and '1' are respectively made to correspond to '-1' and '+1' against corresponding two or four converted codes and by using one of the converted codes, in which DSV containing the converted code being processed approaches '0' against the DSV to the last of the previous converted codes and the first bit being processed is the same as the last bit of the previous converted code, the 8-bit information words are encoded and converted into 14-bit block codes.