PURPOSE: To utilize a selected tone color or automatic accompaniment to effectively play an electronic musical instrument by easily setting a proper temperament in accordance with the selection state of tone color or automatic accompaniment.

CONSTITUTION: Detection signals S11 and S12 are sent from a switch closing state detection part 13 to a tone color selecting switch 11 and an automatic accompaniment selecting switch 12. A switch closing detection signal S31 is sent to a temperament setting part 14 from the switch closing state detection part 13 based on detection result signals S21 and S22 as the detection results. A temperament is determined by the temperament setting part 14. A determined temperament information signal S41 is sent to a musical sound generating part 15, and an automatic accompaniment information signal S51 supplied from an automatic accompaniment memory 16 and a key depression information signal S61 from a keyboard 19 are discriminated by a code discriminating part 17, and musical sounds adapted to the temperature determined by the temperament information signal S41 from the temperament setting part 14 are produced from a speaker 20 connected to a musical sound generating part 15 based on a code information signal S71 from the code discriminating part 17 and key depression information signals S81 and S92 from keyboards 18 and 19.