Abstract: The trochoid pump includes an outer gear rotor and an inner gear rotor, which are different in number of teeth from each other, pressure chambers defined by adjoining teeth of both rotors and an end plate. The pressure chamber volumes are increased or decreased in accordance with rotations of both rotors. An intake opening communicates with the pressure chambers whose volumes are gradually increasing, out of the pressure chamber and an outlet opening communicates with the pressure chambers whose volumes are gradually decreasing. A starting end of the intake opening starts to be opened at a minimum gap position or a neighborhood position thereof. The starting end of the intake opening can be opened at a position advanced through a rotary angle of 4 degrees in the rotating direction of both rotors from the minimum gap position.