PURPOSE: To attain high speed write of data by writing a part of a serial data fetched to a prescribed address of a memory cell array directly so as to be written in an address consecutive to the address of a written data.

CONSTITUTION: Serial data transferred by a data transfer means 1 is stored in a data storage means 4 sequentially and a part of data such as a head item or a final item in a data group is written by 1st write means 9, 10 directly into a memory cell array 7. Then a 2nd write means 6 writes a stored data in the data storage means 4 into the memory cell array 7 at the write of the 1st write means 10. In this case, the data written by the two write means are written they are written in consecutive addresses. Thus, the data in the data storage means 4 is transferred to the memory cell array by utilizing the time required to transfer the part of the data to the data storage means 4, it is not required to stop the data transfer and the write processing is attained at a high speed.