An underwater communication device (100) is provided with a voice interface (4), a transceiving unit, a voice quality converting unit and a body (1), etcetera. A bone conduction/throat microphone unit, assembled in the voice interface (4), converts the vocal cord vibrations of a diver to voice signals. The voice quality converting unit converts the voice signals to voice signals based on a clearer voice. A transmitting unit, assembled in the transceiving unit, transmits the converted voice signals to the outside. A receiving unit, assembled in the transceiving unit, receives voice data which is transmitted from the outside. A bone-conduction speaker unit, assembled in the voice interface (4), outputs vibrations corresponding to the voice data received by the receiving unit. Attachment equipment (1, 2, 3) are put on a diver in a state where the bone-conduction speaker unit is in attached to the diver. The receiving unit and the bone-conduction speaker unit are integrally attached to the body (1).