PURPOSE: To improve the quality of a musical performance by converting keying strength information that key event information contains as specified and driving a key.

CONSTITUTION: In a random access memory(RAM) 12, the work area for a CPU 10, and various registers, flags, etc., for controlling this automatic playing device are defined. This RAM 12 stores information showing whether or not the soft pedal is pressed. In addition to the key event information, event information on the soft pedal is previously stored as musical performance information and when the soft pedal event information is read out during an automatic musical performance, whether or not the soft pedal of the automatic playing device is turned on or off is stored in a specific area of the RAM 12. When the key event information is read out in this state, keying strength included in this event information is converted according to a characteristic line if the ON information on the soft pedal is stored, and a key is driven according to the keying strength information obtained by the conversion.