There is a demand for arranging music composed using multiple instruments for a solo piano because there are several pianists who wish to practice playing their favorite songs or music. Generally, the method used for piano arrangement entails reducing original notes to fit on a two-line staff. However, a fundamental solution that improves originality and playability in conjunction with score quality continues to elude approaches proposed by extant studies. Hence, the present study proposes a new approach to arranging a musical score for the piano by using four musical components, namely melody, chords, rhythm, and the number of notes that can be extracted from an original score. The proposed method involves inputting an original score and subsequently generating both right- and left-hand playing parts of piano scores. With respect to the right part, optional notes from a chord were added to the melody. With respect to the left part, appropriate accompaniments were selected from a database comprising pop musical piano scores. The selected accompaniments are considered to correspond to the impression of an original score. High-quality solo piano scores reflecting original characteristics were generated and considered as part of playability.