PURPOSE: To efficiently use a data communication line and to improve the processing efficiency, by temporarily holding data of a receiving buffer on a floppy disk when a fetching in buffer is fully occupied and transferring the data to a file controller after the data reception is terminated.

CONSTITUTION: Plural data successively received through a communication line are stored in fetching in buffers 521W52m of an RAM22 under the control of the microprocessor 21 of a storage controller 2. The data of the buffers 521W52m are transferred to a file controller 1 through a parallel I/O port 26 and stored in a disk file 14 under the control of a microprocessor 11. When the data are stored in the file 14 and the buffers 521W52m are fully occupied, the data of a receiving buffer 51 are temporarily stored on a floppy disk 24 and, after the data reception is completed, the data temporarily stored on the disk 24 are transferred to the controller 2. Thus the communication line is efficiently used.