An encoding apparatus detects a bit repeating portion in a mantissa part bit string. The mantissa part bit string is a part of a bit string of a floating point number and corresponds to a mantissa of the floating point number. The floating point number has a sign, an exponent, and the mantissa. The bit repeating portion includes repetitions of a particular bit pattern up to a tail of the mantissa part bit string. The encoding apparatus encodes the bit string of the floating point number into a converted bit string with a first part bit string and a second part bit string. The first part bit string includes a sign part bit string, an exponent part bit string, and a part of the mantissa part bit string that exclude a bit string portion after a secondary repetition of the particular bit pattern. The second part bit string specifies the particular bit pattern in the first part bit string.