An automatic player piano has various sorts of individuality due to differences in size, design margins applied to the component parts and a difference in electric characteristics of system component parts so that key position signals contain error components due to those sorts of individuality; plural feedback control loops are created between the key sensors and key actuators, and the error components are eliminated from the current key positions through the normalization; even if an original performance is reenacted through the automatic player piano different from that used in the recording, the feedback control loops cause the key actuators to force the keys to move along reference trajectories determined on the basis of the music data codes, whereby the manufacturer makes the key sensors shared between the recording system and the automatic playing system.