Abstract

An automatic accompaniment apparatus for an electronic musical instrument comprises a performance data generating device, a key-count detection device, a chord data memory, a chord data decision device and an accompaniment performing device. The performance data generating device generates key depression data and tone pitch data in response to a performance operation. The key-count detection device detects a count of depressed keys in the performance operation based on said key depression data, and generates data representing the count of depressed keys. The chord data memory stores previous chord data representing a chord type and a root note, and the previous chord data corresponds to a performance operation played previously. The chord data decision device detects a chord pattern corresponding to said count of depressed keys and said tone pitch data and, when said count of depressed key corresponds to a specific count, decides chord data based on said chord pattern and said previous chord data. The accompaniment performing device performs an accompaniment based on said decided chord data.