A mobile phone manages display area 12 as twelve partial areas obtained by dividing the display area into a matrix of four rows and three columns, which is identical to an arrangement of keys of a numeric keypad; if plural windows are displayed in a partial area arranged in the same position as a pressed key, assigns a key to each of the windows displayed in the partial area, the key being for selecting the window, and notifies the keys; and if one of the notified keys is pressed, selects a window to which the pressed key has been assigned.