To provide a data transfer device that can speed up data transfer between I/O which is a data processing part and an image memory which is a storage device.

A write buffer 11 (or read buffer 12) is disposed as a buffer memory between an image memory 2 and first I/O 141 (or second I/O 142). Data, transferred from either, are stored temporarily in the write buffer 11 (or read buffer 12) before transferred to the other. Data writing to (or reading from) the image memory 2 is executed between the image memory 2 and the write buffer 11 (or read buffer 12).