A loop-type data transmission/reception network system has a plurality of data processing stations and a single data transmission/reception route which interconnects said stations in a loop for transmitting necessary data between the stations, each of the stations comprising: (a) means for detecting a break-down in the data transmission/reception route between the station itself and the preceding station; (b) means responsive to the detection of a break-down in the data transmission/reception route between the station itself and the preceding station by the detection means for transmitting break-down information to the subsequent station; and means for reversing the transmission direction in the data transmission reception route in accordance with the break-down information transmitted by the break-down information transmitting means.