an 8 / 9 coding apparatus which suppresses the dc component of input data to be recorded on a magnetic tape by converting the 8 - bit input data to 9 - bit coded data , provided with a cdsc table for the cdsc data , that is , the data of the complement of 2 of the cumulative value of bits in a symbol included in coded data based on the input data . in a dsvc adder , cdsc data is cumulatively added by a polarity in accordance with polarity data , dsvc data indicating the complement of 2 of the cumulative value of the bits for every sector is generated , and an msb bit thereof is output as msb data to a table selector . the table selector outputs a table switching signal generated based on the polarity data and the msb data to a data table , a polarity table , and the cdsc table . the tables are selectively used based on this switching signal .