A transmission device configured to transmit a transmission bit string which is an arrangement of a unit bit string of multiple N bits includes: a conversion unit configured to convert the unit bit string into a converted bit string in accordance with a conversion table obtained by obtaining an error rate wherein a k'th bit out of the N bits is in error; obtaining an error expectancy which is an expectancy that a significant bit of the N bits in the unit bit string will err; and creating a conversion table that correlates the unit bit string and a converted bit string obtained by converting the insignificant bit of the unit bit string to a smallest error expectancy bit pattern which is a bit pattern that minimizes the error expectancy of the multiple bit patterns; and a transmission unit configured to transmit the converted bit string.