Abstract: An automatic accompaniment system for use with an electronic musical instrument of a type having keyboard arrangements, which is capable of automatically sounding chords and basses in accordance with a predetermined rhythm of a selected music, the basses of which are each formed by some of tones forming each chord in the case where the right and left hands of a player are used to play the melody and an accompaniment, respectively. To this end, the system includes a counting circuit composed of a binary counter and a decoder, a high frequency pulse generator, a plurality of logical gating elements and a rhythm pulse generator.