(57) An electronic musical instrument extracts a pitch from an input waveform signal by a pitch extracting circuit (P1 ∼ P6), and directs a sound source circuit (9) to generate a musical tone at the pitch based on the extracted pitch. The sound source circuit (9) electronically generates musical tones at the pitches according to the performance. The pitch extracting circuit (P1 ∼ P6) obtains a fundamental period of the input waveform signal by detecting the time interval (t1) between these first two zero-cross points after two positive peak points of the input waveform signal are detected, by detecting a time interval (t2) between first two zero-cross points after two negative peak points of the input signal waveform are detected, or by detecting both the time intervals (t1, t2).