A wearable communication device includes a bone conduction actuator which is applicable for being in contact with a user's wrist, hand, back of the hand, finger or nail in order to transmit voice signals. The user inserts the user's finger into the user's ear canal, or touches the user's finger to a part near the user's ear, or puts the user's fingertip or nail on the user's ear canal so as to block the user's ear canal when the user uses the wearable communication device. Also, the wearable command input device includes a first part for detecting shock or acceleration which arises when the user taps the user's fingertip on the surface of an object or when the user taps the fingertips mutually and which is transmitted through the user's finger, a second part for detecting specific frequency components which are included in signals from the first part and for detecting the presence or the absence of the tap of the finger of the user, and a part for determining and executing commands based on series of signals output from the second part.