In displaying a music score by using a computer, there is provided a function for matching an in-music position being updated in a computer with an in-music position being played. According to the in-music position, display update is controlled. Space of music score display is divided into several partitions. The timing of updating each partition is defined as the moment when the in-music position in the computer has arrived at the position in the page obtained by predetermined function from the position of the page divided and the partitions are successively updated. Thus, it is possible to realize smooth display update capable of displaying the preceding partition and holding the display with a sufficient width before and after the position being played. Here, a plurality of timing input means are provided for matching the in-music position required here, so that a trace shift in the lower level can be corrected by means having a higher-level reliability when necessary. When playing in concert, the music score is different for each part but the display update can be controlled by supplying the in-music position information.