PURPOSE: To provide a print data acquiring device which can acquire the print data on the application software and can store these data in a file by providing a storage means which stores the address of a print function and a means which writes the address of a data acquiring function in the storage means in an operating system OS.

CONSTITUTION: A data acquiring function 3 acquires the data and stores them in a file, and a secondary storage 6 stores the data. A print data acquiring device makes the function 3 resident in an OS and rewrites the address of a print function of a table 1 into the address of the function 3. This address rewriting processing eliminates the transmission lines 8 and 9. After the operation of the data acquring device, the print data on the application software 4 are sent to the function 3 through the transmission lines 10 and 11 owing to the rewriting of the table 1. The function 3 carries out the prescribed processing and sends the data to the storage 6.