This paper describes a detection method of indication action and the corresponding indicated area with a stick. In human communication, there exists ambiguity of indication action, so we need some useful knowledge about indication action. We propose a detection method of the indicated area based on the knowledge which we clarify by means of observation of some lectures. We formulate a potential value of intentional indication action of an instant, and cast the value for printed area using a weighted vote method. An experimental result shows that 85 percents of indication actions are correctly detected.