AbstractConstruction of an expert system is frequently studied in knowledge engineering. Hence, in constructing sophisticated expert systems, analysis of the human thinking process and the human memory mechanism is essential. This is because humans in the real world have problem‐solving abilities.This paper presents the expert system “MUSAS” (musical arrangement system) for musical arrangement, to study the mechanisms and processes in human problem solving. Since musical arrangements have both a theoretical and emotional side, the former being text knowledge and the latter being heuristic, text knowledge is used to propose chords.Finally, the basic construction of MUSAS is given, and the method of application of a knowledge‐based system for musical arrangement along with the system process and experimental results are presented.