A music generation device includes: an acquisition unit that acquires first stream data and second stream data different from the first stream data; an accompaniment generation unit that generates accompaniment information, which is music data indicating an accompaniment, based on a change in the first stream data; a melody generation unit that generates melody information, which is music data indicating a melody, based on a change in the second stream data; a melody adjustment unit that adjusts the melody information in accordance with a key of the accompaniment indicated by the generated accompaniment information; a music combining unit that combines the accompaniment information and the adjusted melody information to generate musical piece information; and an output unit that outputs the generated musical piece information.

Provided is an automatic music playing control device that provides an instruction of playing music, the control device implementing natural music playing capable of expressing the timing and voicing in live music playing of a musical instrument by a player. The automatic music playing control device includes at least one processor, and the at least one processor selects a voicing pattern corresponding to a combination of the probabilistically-selected number of sounds to be emitted and a decided voicing type corresponding to a range from among a plurality of voicing patterns based on a scale decided according to the tune and chords of a music piece and instructs a sound source to emit a chord voiced based on the selected voicing pattern.

Provided is an automatic music playing control device that automatically plays chords to achieve a good music playing. The automatic music playing control device has at least one processor, wherein the at least one processor probabilistically selects any one of a plurality of timing types that defines the number of sound emissions, probabilistically selects any one of a plurality of note timing tables that defines sound emission timings, corresponding to the selected timing type, and instructs a sound source to emit a chord at a sound emission timing based on the selected note timing table.