Performance data for a plurality of parts are received, and timing data included in the performance data for these parts are combined together to provide a time series data common to the parts. Layout of individual measures and layout of notes within each of the measures and beats are determined on the basis of the combined timing information, so that the thus-determined layout is defined as a common layout for shared use in the individual parts. In accordance with the common layout, note marks are allocated to rows of staves corresponding to the parts on the basis of the part-specific performance data. Thus, it is possible to achieve musical score layout having an enhanced appearance with all the corresponding beat positions (time axes) of the rows of staves accurately aligned with each other. Further, each ornament is detected from among the performance data so that the ornament note group is presented on the staves using a predetermined ornament mark. In addition, the notes represented by the performance data relating to the ornament are subjected to a quantization process, and these notes are presented on the staves in a combination of the ornament mark and note marks of the quantized data. Furthermore, each note group corresponding to an arpeggio or glissando performance is detected from among the performance data so that the note group is presented on the staves in a combination of a predetermined performance style mark and marks representative of the notes.