An encoding apparatus that converts m-bit data words into n-bit code words, where m and n are both integers and satisfy an expression 2n≧2m×2, includes a first conversion table in which 2m m-bit data words are associated with 2m n-bit code words selected from 2n n-bit code words, a second conversion table in which the 2m m-bit data words are associated with 2m n-bit code words that have been selected from the 2n n-bit code words and that do not overlap with the 2m n-bit code words in the first conversion table, and an encoder configured to select and output an n-bit code word with which an m-bit data word that has been input is associated in the first conversion table or an n-bit code word with which the m-bit data word that has been input is associated in the second conversion table, the selected and output n-bit code word having a smaller number of symbols “1”.