PURPOSE: To obtain information which is necessary for the improvement of playing technique by finding an error in musical performance by a performance practice based upon an example performance.

CONSTITUTION: The difference between the musical sound information of a musical performance by a professional and the musical sound information of a performance by a player is found for each piece of musical sound information and stored in a C area of a RAM as the performance practice is advanced and after the performance practice of one piece of music is completed, pieces of musical sound information on an object of evaluation specified with an evaluation object SW are rearranged in the decreasing order of the absolute values and stored (steps S31-S33, S45, and S55). The correction direction of the performance is indicated with '+' and '--' according to the signs of their differences (steps S33-S38. S46-S50, and S56-S60). Further, the correction quantity of the performance is calculated An percent and displayed and when the data come to the end, points are calculated in the decreasing order of differences larger than a specific value (steps S39-S42, S51-S54, and S61-S64).