In a data transfer apparatus 10, first, second, third data transmitters 141, 142, 143 are located in a data transmission device 11. Data which must not be influenced by delay of transmission timing of the other data are stored in first, second, third data transmitters 141, 142, 143. The data selector 16 selects these at a predetermined order or frequency to be transmitted to a data reception device 12. As a result, when an uncorrectable trouble is detected by a trouble detecting section 27, a re-issue instruction 21 is issued at a predetermined timing based on information stored in an information round robin section 36. The corresponding data from the corresponding data transmitter 141, 142, or 143 is selected by the data selector 16 and then re-sent.