The present invention provides a method of printing application data. In this method, a print request and ASP certification data for accessing an application server are transmitted from a client computer to a printer of a print shop connected to the client computer and the service provider via a network capable of providing an application service, such as the Internet available for unspecified users. The printer is operable to access the application server directly according to the ASP certification data so as to receive print data from the application server and output the print data. The present invention can solve problems caused when the client computer issues a print request to the printer of the print shop via the network, so that the requirement for the client computer to acquire application software from the application server is eliminated to provide a reduced time-period of a printing operation.