A musical tone control apparatus comprises a main unit and at least one detector for detecting movement of player's finger, hand and the like. The main unit can be mounted on a player's wrist by use of a belt. When plural detectors are provided for detecting movements of player's fingers, tone color, tone pitch of musical tone or key-on timing is controlled based on combination of bent fingers. In order to detect bending of each finger, a joint switch is provided for each finger. In order to prevent deviation of key-on signals, a comparator is further used for comparing the predetermined threshold value with detection value corresponding to the bending of each finger so that the key-on signal is generated when the detection value exceeds the threshold value.