A print controlling device operated on a multi-task operating system to process application data according to a printer driver is provided. The print controlling device includes an input device, a display device, a modifying system to modify the application data into a printable format, a communication interface, an output device determining system to determine to which devices between the printing device and the display device the printable-formatted data is output, an activating system to activate a displaying program in a separated operating task from the currently-executed operating task having been executed for the printer driver, a transmission system to transmit the printable-formatted data to the printing device, and a terminating system to terminate the currently-running operating task for the printer driver when the activating system activates the displaying program in the separated operating task.