PURPOSE: To decrease the number of times of accesses in a magnetic disk and to shorten print processing time by changing the size of an output buffer in correspondence to the size of file information.

CONSTITUTION: A printing system is composed of a keyboard 5 to input a command, a system control means 12 to house a command program, a magnetic disk device 9 to house the file information, an output buffer to house information, which are read from the device 9, and to be composed of a RAM, a printer buffer 8 and a printer 7, etc. When the command to designate the filing name of the file information and the size of the output buffer is inputted in order to output the file information of the device 9 from the keyboard 5 to the printer 7, the means 12 sets the output buffer 14 to the designated size and the file information are read from the device 9 and housed to the output buffer 14. Then, the file information are successively read from the output buffer 14 for the unit of the size of the printer buffer 8 and outputted to the printer 7.