<p>The present invention provides a highly efficient and highly reliable scroll fluid machine that suppresses fluctuations in port aperture area during each revolution of an orbiting scroll while ensuring port aperture area. In the present scroll fluid machine, suction ports for sucking in a working fluid are disposed on a second base plate so as to have openings in a vicinity of a winding start end portion of a second spiral tooth, and near an inward facing surface of the second spiral tooth at a position that is separated by an involute angle of approximately 90° from the winding start end portion of the second spiral tooth. Discharge ports for discharging the working fluid are disposed on a first base plate so as to have openings in a vicinity of a winding start end portion of a first spiral tooth, and near an inward facing surface of the first spiral tooth at a position that is separated by an involute angle of approximately 90° from the winding start end portion of the first spiral tooth.</p>
