To realize a data transmission system by designating the number of times of transmission for ensuring the reliability of whole transmission data, and reducing transmission information amounts.

In a transmitting device, a voice encoding means 1 quantizes/ encodes each parameter obtained by analyzing and separating an input voice signal 101, and generates an input voice signal parameter 102, and a transmitting part 2 transmits high significant code words, obtained by operating transmission path encoding and prescribed duplication, to a transmission path plural number of times, and low significant code words to the transmission path at least one time as transmission data 103. In a receiving device, a receiving part 3 receives the transmission data 103 from the transmission path, and operates the combined restoration of the plural correct high significant decoded words selected according to an error correction/detection code with at least one low significant decoded word, and a voice decoding means 4 decodes an obtained decoded voice signal parameter 104, and outputs a decoded voice signal 105 generated by connecting each parameter.