A set of formation data codes, which includes action event codes and duration codes, is loaded in an automatic player piano, and a controller interprets the action event codes for driving the solenoid-operated key actuators; since the solenoid-operated key actuators slowly push the associated keys, the hammers do not reach the strings, and any piano tone is not produced; the plungers make the keys sunk to different depth so that the keys are laid on a artistic pattern; the controller sequentially changes the artistic pattern, and offers an artistic visual expression to the audience.