PURPOSE: To provide the method for controlling generation and elimination of a window in a way that the conversation executed at present via the window is not disturbed by the generation or elimination of other window.

CONSTITUTION: The user designates a conversation form being one of the sequential, parallel and urgent modes for the program used for conversation with the user and makes a request to a conversation management program 200. The conversation management program 200 allows the conversation of a limited number of programs at once in the sequential conversation mode, allows conversation in parallel with the conversation by other program in the case of the parallel conversion mode, and allows the conversation with priority by stopping the other conversation in the case of the urgent conversation mode. The state of the conversation in this case is displayed by a conversation state icon 40.