A score data displaying/editing apparatus comprising: a storage section (103, 104; 203) that stores score data including a plurality of note data, each of the note data including (a) fundamental attribute data composed of pitch data indicative of a pitch of a sound and sounding period data indicative of a sounding period of the sound, and (b) a plurality of types of additional attribute data indicative of attributes other than the pitch and sounding period of the sound; a display section (105, 204), a selection section (101, 106; 20, 205, 206) that selects one or more of the plurality of types of additional attribute data; and a display section (101, 20) that is adapted to display, for each of the plurality of note data, a pictorial figure or symbol indicative of contents of the fundamental attribute data included in the note data and a letter, numeral, symbol or pictorial figure indicative of contents of the additional attribute data included in the note data, and selected by said selection section, simultaneously in proximity to each other, characterized in that said score data displaying/editing apparatus further comprises: a state change section (101, 106; 20, 205, 207) that sets, to a changeable state, one of the additional attribute data for each of which the letter, numeral, symbol or pictorial figure indicative of the contents is being displayed by said display section; and a data change section (101, 106; 20, 205, 208) that changes the additional attribute data having been set to the changeable state by said state change section, or sets the additional attribute data, having been set to the changeable state, to a non-changeable state without changing the same, wherein the plurality of note data constituting the score data are segmented into a plurality of part data corresponding to a plurality of parts, and said state change section selects one of the additional attribute data of one of the types, selected by said selection section, on the basis of at least one of the pitch data, sounding period data and additional attribute data included in the part data that include the one additional attribute data, and then said state change section sets the selected additional attribute data to a changeable state. a storage section (103, 104; 203) that stores score data including a plurality of note data, each of the note data including (a) fundamental attribute data composed of pitch data indicative of a pitch of a sound and sounding period data indicative of a sounding period of the sound, and (b) a plurality of types of additional attribute data indicative of attributes other than the pitch and sounding period of the sound; a display section (105, 204), a selection section (101, 106; 20, 205, 206) that selects one or more of the plurality of types of additional attribute data; and a display section (101, 20) that is adapted to display, for each of the plurality of note data, a pictorial figure or symbol indicative of contents of the fundamental attribute data included in the note data and a letter, numeral, symbol or pictorial figure indicative of contents of the additional attribute data included in the note data, and selected by said selection section, simultaneously in proximity to each other, characterized in that said score data displaying/editing apparatus further comprises: a state change section (101, 106; 20, 205, 207) that sets, to a changeable state, one of the additional attribute data for each of which the letter, numeral, symbol or pictorial figure indicative of the contents is being displayed by said display section; and a data change section (101, 106; 20, 205, 208) that changes the additional attribute data having been set to the changeable state by said state change section, or sets the additional attribute data, having been set to the changeable state, to a non-changeable state without changing the same, wherein the plurality of note data constituting the score data are segmented into a plurality of part data corresponding to a plurality of parts, and said state change section selects one of the additional attribute data of one of the types, selected by said selection section, on the basis of at least one of the pitch data, sounding period data and additional attribute data included in the part data that include the one additional attribute data, and then said state change section sets the selected additional attribute data to a changeable state. a state change section (101, 106; 20, 205, 207) that sets, to a changeable state, one of the additional attribute data for each of which the letter, numeral, symbol or pictorial figure indicative of the contents is being displayed by said display section; and a data change section (101, 106; 20, 205, 208) that changes the additional attribute data having been set to the changeable state by said state change section, or sets the additional attribute data, having been set to the changeable state, to a non-changeable state without changing the same, wherein the plurality of note data constituting the score data are segmented into a plurality of part data corresponding to a plurality of parts, and said state change section selects one of the additional attribute data of one of the types, selected by said selection section, on the basis of at least one of the pitch data, sounding period data and additional attribute data included in the part data that include the one additional attribute data, and then said state change section sets the selected additional attribute data to a changeable state.