Musical performance system, musical instrument incorporated therein and multi-purpose portable information terminal device for the system

Mixing musical instrument (1) and A (2) is music performance system, and user uses A (2) is control mixing musical instrument (1); When the user to with the musical instrument (1) and A (2) pair, the musical instrument (1) converting identification code of the display screen (6) is machine of the image, for example QR code (8) image, and A (2) (26) absorbs the QR code (8) image with the image collecting device; A (2) in QR code (8) image for identification code, and a memory in memory; , Wherein the condition of typing, surface of the mixing musical instrument (1) by the identification code A (2), relative to the user a freescale of the pair is simple and quickly.