An electronic musical score apparatus 1 includes display units D1, D2 connected to each other to be openable and closeable, and can convert a writing made on display portions 11, 12 by a user into annotation data 1, associated with musical score page data but being manageable separately from the musical score page data, and store the annotation data 1. When an image of the associated musical score page data is displayed together with an image of the annotation data 1 on the display portions 11, 12 and then the user rewrites the annotation data 1, the electronic musical score apparatus 1 can provide a write history for the annotation data 1 by storing the annotation data 1 before the rewriting as first-generation annotation data 1 and storing the annotation data 1 after the rewriting as second-generation annotation data 1.