An application linking technology enables data formatted among many-to-many applications to be communicated. From a window displayed by at least one first application, a necessary information item for an operation of at least one second application is collected. When the collected information items contain items not matching the data format of the second application, data conversion is performed on an unmatched information item to a data format of the second application. A matching information item and a data-converted information item whichever is necessary to the second application is transmitted. A processing result transmitted from the second application is received. Data conversion is performed on an unmatched processing result to a predetermined format when a processing result contains data not matching the predetermined format. A processing result matching a predetermined format and a data-converted processing result is output in a predetermined position of the window with a predetermined data attribute.