An electronic musical instrument internally stores automatic performance data. The electronic musical instrument reads automatic performance data to perform an automatic performance, while incrementing melody tone pitch data contained in the automatic performance data. The electronic musical instrument obtains a valve state signal from an operated state of a plurality of performance operators. The electronic musical instrument automatically generates pitch data corresponding to a pitch of a voice on the basis of the melody tone pitch data. The electronic musical instrument extracts tone pitch candidates on the basis of the valve state signal, and determines a tone pitch in accordance with the automatically generated pitch data and the tone pitch candidates. The timing at which the determined tone pitch matches the melody tone pitch data is regarded as the timing to increment the melody tone pitch data.