An electronic musical instrument includes a tuning device, a keyboard, a tone generator, a microphone, a measurement unit, and a display attached to the backside of the housing. The tone generator generates a plurality of reference tones in response to the operation of the keyboard, while the microphone receives a plurality of musical tones, which are generated by at least one musical instrument subjected to tuning. Different tone colors can be applied to the reference tones. The measurement unit measures a plurality of pitch differences between the reference tones and the musical tones subjected to tuning, so that the display displays the pitch differences in comparison with each other.