PURPOSE:To prevent erroneous setting of control information and to simplify the setting operation by instantaneously setting the same control information at each of a plurality of channels. CONSTITUTION:In a digital mixer for controlling a plurality of channels based on control information set for these individual channels, a display area 26 for displaying each channel and corresponding control information is displayed in a display control section 22 and display unit 24. Based on these displays, a display area 26 that becomes a copy source and a display area 26 that becomes a copy destination are specified by a position input control section 16. In accordance with this specification, the display control section 22 displays a mark in the display area 26 for copy source indicating that the display area is for copy source, and a mark in the display area for channel for copy destination indicating that the display area is for a copy destination, respectively. A CPU4 supplies control information about copy source as control information for a control object in a copy destination.