An apparatus for practicing playing music on a musical instrument provides a stepped lesson comprised of a series of lesson steps about a subject music piece, each step providing practicing materials for a user to master for playing the subject music piece. The lesson steps are given to the user step by step. The apparatus stores a music-playing data set of a subject music piece for a reference and a music-playing data sets of the stepped lesson, and comprises a music-playing input device for the user to input music-playing manipulations. The apparatus judges, at each of the lesson steps, the achievements of the user in comparison with the reference music-playing data. The apparatus keeps a pass/fail score table for recording pass/fail judgments about the achievements of the user with respect to the respective lesson steps. The user can practice lesson steps selectively with reference to the pass/fail score table about his/her achievements.