An apparatus and method for converting data between a floating-point number and an integer is provided. The apparatus includes a data converter configured to determine a sign of input binary data and an output format to which to convert the input binary data and convert the input binary data into a one's complement number based on the sign and the output format of the input binary data, a bias value generator configured to determine whether the input binary data has been rounded up based on a rounding mode of the input binary data and generate a bias value accordingly; and an adder configured to convert the input binary data into a two's complement number by adding the one's complement number and the bias value.