in a key depression indicating device for an electronic musical instrument capable of visually indicating which keys are to be depressed on a keyboard, the device includes a plurality of indicators provided correspondingly to a plurality of keys of the keyboard. Illumination of each indicators is so controlled by an illumination control means that an indicator corresponding to a succeeding note is lighted up at a timing, for example, a 4-th note's length ahead of the timing to depress the key irrespective of any length of the preceding note. Thus, even when a complicated music performance including a train of a plurality of consecutive short notes as a 32nd note is required, the indicators corresponding to the preceding as well as the succeeding notes in the train are each lighted up at a timing, i.e. the 4-th note's time length ahead of each actual key depression timing for the music performance. In this way, since there is given a sufficient ready time for each note, the player of the instrument is able to perform a smooth key depressing operation in accordance with the key-depressing indications given by the device.