Abstract: An electric tutor is assembled with an upright piano having a keyboard and a key stop rail laterally extending over the rear end portions of the black/white keys, and includes a comb-like flexible indicator attached to the key stop rail, wherein the comb-like flexible indicator has flexible insulating strips connected to a rigid printed board attached to the key stop rail by means of connectors and lying on the black/white keys, optical indicators attached to the flexible insulating strips and signal lines printed on the back surfaces of the flexible insulating strips for selectively supplying driving signals to the optical indicators for radiating light, thereby guiding the fingers of a player in accordance with a music score.