PURPOSE: To smoothly move the knob of a sound volume adjuster at the time of reproducing movement of the sound volume adjuster in accordance with knob movement position data by a motor by storing sound volume adjuster knob position data of manual operation in a storage device.

CONSTITUTION: Knobs of plural sound volume adjusters provided in a mixing console are manually operated to store knob movement position data of each certain unit time in a storage device (data generator) 2. This stored knob movement position data is read out, and the motor is driven to reproduce knob movement to knob movement positions of sound volume adjusters 1a and 1b. At the time of this reproducing of knob movement, knob movement position data of each of plural divided times obtained by dividing the unit time is generated by calculation in accordance with knob movement position data of each unit time read out from the storage device 2. The motor is driven to continuously move knobs to calculated knob movement positions of sound volume adjusters 1a and 1b, thus smoothly reproducing knob movement of sound adjusters 1a and 1b.