A shift controller 113 of a focus management unit 110 decides whether the component designated by a focus position has a handler 131 when shifting a focus. As a result of the decision, if the component has the handler 131, the shift controller 113 shifts the focus in accordance with the processing described in the handler 131. Unless the component has the handler 131, the shift controller 113 decides whether it can shift the focus in accordance with a general rule 112a. As a result of the decision, it carries out control in a manner as to shift the focus if it can shift the focus, but not to shift the focus if it cannot shift it.