A water pressure driven tooth brush according to embodiments includes a hose to be connected to a faucet, a water pressure power generator to generate rotating force by receiving water pressure through the hose, and rotary tooth brush hairs rotated by the water pressure power generator. The water pressure power generator includes a cylindrical housing serving as a tooth brush handle and having a water supply pipe and a water exhaust pipe at a rear portion thereof, and at least one driving shaft at a front portion thereof, a water turbine installed in a rear chamber formed in the cylindrical housing and rotated by pressurized water, and a reduction module installed in a front chamber formed in the cylindrical housing and coupled to a rotating shaft of the water turbine to transfer reduced rotating force to the driving shaft.
