PURPOSE: To enable a user to effectively enjoy music by displaying a picture accurately corresponding to contents of each parameter indicating a characteristic of an inputted musical sound.

CONSTITUTION: Pictures of musical instruments are preliminarily displayed on a display device 13 correspondingly to tone colors in which an electronic musical instrument 5 can emit sounds or representative tone colors out of them. When the electronic musical instrument 5 is played, playing information is transmitted from the electronic musical instrument 5 to a CPU 11, and the CPU 11 detects the volume of musical sounds in each tone color from playing information. Tone colors of musical instruments detected in this manner and information related to levels of musical sounds in these tone colors are inputted from the CPU 1 to a display control part 11, and this part 11 changes the size of the picture of a musical instrument corresponding to the tone color, in which sounds are emitted at present, out of pictures of musical instruments displayed on the display device 13 in accordance with the level of the musical sound signal of this tone color based on these information. Thus, he can effectively enjoy the musical performance.