A chord analysis apparatus which includes a table memory for memorizing a plurality of sound timing patterns in a performance section of a predetermined number of beats, a plurality of tone pitch difference patterns corresponding with the sound timing patterns and a plurality of harmonic tone information data corresponding with the tone pitch difference patterns. In the tone pitch difference patterns, each difference in tone pitch between adjacent tones is represented by the number of semitones. After a performance information data of a desired musical tune has been divided each at two times, a pattern corresponding with the sound timing and tone pitch difference patterns in each divided section is searched at the table memory to read out a harmonic tone information data corresponding with the searched pattern thereby to detect each chord of the divided sections based thereon.