For each performance part, a database stores therein a plurality of part performance data. The part performance data for each part includes a sound generation pattern and tone data corresponding thereto. A query pattern indicative of a sound generation pattern to be made an object of search is input by a user. A search is made through the database for part performance data including a sound generation pattern matching the query pattern. In response to a user's operation, one part performance data is identified from among searched-out results, and the sound generation pattern of the identified part performance data is instructed as a new query pattern. Then, a further search is made through the database for part performance data including a sound generation pattern matching the new query pattern. The searched-out pattern can be edited by the user and a further search can be made based on the edited pattern.