To efficiently perform character input in a limited display space by designating an input character object area, overlapping it on other display, showing a display window in the input character object area and expanding characters.

A cursor 37 is moved among the display spaces of equalizer names 41-1 to 41-10 by the operation of cursor keys on and under a remote controller, a desired characteristic is selected from among stored equalizers, further, and the name of an equalizer that is selected by pressing an enter key is shown in an expanded way. That is, when a display 41-2 of 'MEMORY 2' is selected, the display window of the display 41-2 is expanded and overlapped on a display 41-3 and shown. The equalizer name 41-2 is shown in an expanded way, and the display of the equalizer name 41-2 is expanded from 1/4 square font to 1/2 square font.