PURPOSE: To improve a noise feeling in a signal after data bit conversion for securing a dynamic range of larger than a specific number of bits when digital audio, etc., is transmitted or recorded.

CONSTITUTION: The rounding circuit 3 of a requantizer rounds 20-bit input data off to 16 bits, and the rounding-off error is taken out by a circuit 7 which obtains an input/output difference and subtracted from an input through a circuit 6 which obtains the difference at the input through a filter 4. At this time, when the input data has a high frequency component, a high frequency component detection part 5 detects it, and a filter 4 is cut to ceases an output to a circuit which obtain the difference. Consequently, the data converting device can be provided which has noise shaping operation ineffective and then does not increase in high frequency noise and never deteriorates the distortion of a low frequency component with the high frequency component even without the noise shaping when the high frequency component is included.