Provided is a data transmission system for automated material handling system in that, in the automated material handling system for transferring the products in course of manufacturing in the semiconductor manufacturing process or the liquid crystal display manufacturing process etc. to each manufacturing station, it switches the communication between the unmanned automatic transfer vehicle and the manufacturing station to the optical communication or the RF communication in readiness for the communication failure between the unmanned automatic transfer vehicle for master and the manufacturing station for slave, it transmits various input and output state data including the communication log data to the higher control system for master or the management computer system of slave/wireless data transmitter-receiver for slave by means of the master and/or slave device through the wire and wireless transmission and reception communication, thereby quickly coping with the operation error through the data analysis.