A data transmitting system uniformly processes and transmits data by taking a plurality of samples of an analog signal and generating bits forming digital words respectively corresponding to the samples, the number of bits representing each sample being switchable between a plurality of values M and N. First input data is supplied in first words of which each consists of M bits and second input data is supplied occurring in second words of which each consists of N bits. An a-th first word in each M-bit first input data is defined as W.sub.a. The first input data is divided into k kinds of sets of (W.sub.nk+1), (W.sub.nk+2), . . . , (W.sub.nk+k), where n is an arbitrary integer. A b-th word in each N-bit second input data is defined as W.sub.b. The second input data is divided into k kinds of sets of (W'.sub.nk+1), (W'.sub.nk+2), . . . , (W'.sub.nk+k), the number of bits of the first words of the set of (W.sub.nk+m) (m being an integer from 1 to k) being equal to the number of bits of the second words in the set of (W'.sub.nk+m). The data separately processed and transmitted in each of the sets.