To obtain the data communication device which eliminates the need for a complicated hardware sequence and a clock generator for generating a delay time on the communication device side, facilitates the design of a logic part of the communication device, and is actualized at low cost.

A master communication device 11 and a slave communication device 12 are connected by a communication line 13; when the master communication device 11 transmits data to the slave communication device 12, a control signal prescribing the operation of the slave communication device 12 is received by the slave communication device 12 and then a data transmit signal is received by the slave communication device 12 a certain time later. In this case, a delay means provided in the communication path of the data transmit signal generates a delay time between the control signal and data transfer signal.