A water pump includes: an upper housing formed with an inlet and an outlet of fluid; a lower housing installed to fit in a lower side of the upper housing, having a receiving space formed therein; a shaft fixing support having a lower part of a protrudedly formed shaft inserted in the center of a bottom part of the lower housing; an impeller installed around the shaft; a rotor configured by having a magnet installed around a rotor core; a stator installed inside the lower housing; a lower cover; a shaft upper part fixing support member installed in an upper side of the shaft erectedly inserted in the shaft fixing support; and a synthetic resin mold member formed with a first synthetic resin mold around an outer side of the shaft fixing support and around the shaft, and a second synthetic resin mold around an outer side of the rotor.