To provide an outside appearance directing device of an electronic musical instrument only by which visual effect by lighting can be obtained in addition to enjoyment in music and which can solve the problem that it is hard to view a keyboard part, a musical score, etc., in the presence of insufficient lighting during a musical performance.

A CPU detects the number of sounding keyboards according to inputted key event information or MIDI information. A light emitting circuit part makes a light emission part 19 to emit light according to the number of sounding keyboards detected by the CPU. The light emission part 19 has sufficient light emission illuminance for lighting and comprises light emitting components such as LEDs. According to the number of sounding keyboards, the light emission quantity, light emission illuminance and light emission colors of the light emission part 19, and their combination are changed. The light emission part 19 is arranged nearby a keyboard 7, atop of the keyboard, nearby a musical score stand 21, or on the back of a main body 22. The light emission part 19 is arranged nearby the keyboard 7 or musical score stand 21 to solve the problem that it is hard to view parts around the hands and the musical score during a musical performance in a place where lighting is not sufficient.