PURPOSE: To reduce the number of times of input output operation by outputting updated data and precedingly operated transaction end information to a journal file in the lump.

CONSTITUTION: A file write means 11 of a transaction performing process 1 writes updated data to an update data buffer 21 in a memory on the occurrence of a data update instruction. A transaction end processing means 12 writes transaction end information to a transaction management table 22 at the end processing of the transaction performing process 1 and writes updated data of the update data buffer 21 and precedingly operated transaction end information of the transaction management table 22 to a journal file 4 in the lump and writes updated data in the update data buffer 21 to a data file 3.