To provide a data transmission system in an assembly line capable of easily changing an arrangement interval of assembly stations, operating securely, and reducing total cost.

In the data transmission system in the assembly line constituted such that data provided in a body to be assembled and conveyed in the assembly line 1 composed of a plurality of assembly stations 3, 3a, 3e, 3m is read and instructions for assembly contents are given to part indication panels 4 provided by corresponding to respective assembly stations, a read station 12 provided with a data read sensor 13 is provided on the upstream side of the assembly stations, read data is sequentially inputted into a sequencer 16 to transmit the data to the part indication panels, and data read sensors 14, 15 for check are provided in any of assembly stations to check the read data with the data read by the data read sensor 13.