A browser is requested to display a text file having a description of a screen structure. The state information on a current state of the embedded device is acquired. An access request for requesting the browser to update, with the acquired state information, a value of at least one node in a document object model (DOM) tree generated from the text file by the browser, is submitted by a state display control program. The at least one node is recorded in an access history list. At a subsequent time, it is determined whether to permit a subsequent access request. If the source of the subsequent access request is not the state display control program, and the at least one node is recorded in the access history list, the subsequent access request is denied.