A field bus interface board is disclosed. The field bus interface board installed in a computer and connected to a field bus line has a main controller for controlling the entire operation of the field bus interface board. A field bus controller controls a data transmission and reception though the field bus line. A dual-port memory is shared between the computer and the main controller for exchanging data with the computer. A buffer memory buffers data transmitted to the field bus line or received from the field bus line, under the control of the field bus controller. A field bus interfacing means transmits data to the field bus line or receives data from the field bus line, under the control of the field bus controller.