1. A musical score display apparatus comprising: connection means for connecting, through a communication line, with an external storage apparatus that stores a display data group including display data of a plurality of musical compositions for displaying musical scores, and a comment data group of each of the musical scores displayed based on the respective display data included in the display data group, the comment data group including a plurality of comment data each indicating a comment relating to the musical score and including date information indicating a creation date and time of the comment; first acquisition means for acquiring, from the external storage apparatus, the display data of one musical composition selected by a user among the display data of the plurality of musical compositions included in the display data group; second acquisition means for acquiring, from the external storage apparatus, the plurality of comment data included in the comment data group of the musical score displayed based on the display data of the one musical composition acquired by the first acquisition means among the comment data group of each of the musical scores; setting means for setting one musical score display level selected by the user among a plurality of musical score display levels respectively corresponding to degrees of complexity; first extraction means for extracting display data used for a musical score to be displayed from the acquired display data of the one musical composition according to the musical score display level set by the setting means; second extraction means for extracting comment data to be displayed from the plurality of comment data included in the acquired comment data group according to the set musical score display level; and display means for displaying the musical score based on the display data extracted by the first extraction means and for displaying the comment data based on the date information included in the comment data extracted by the second extraction means.