<p>A fluid compressor includes a closed case (10) and a cylinder (20) which is arranged in the case and has two opposite ends. A columnar rotating rod (34) is located in the cylinder to be eccentric thereto, and rotatable along with the cylinder. The rod has a spiral groove on the outer circumferential surface thereof, and a spiral blade (42) is fitted in the groove to divide the space between the rod and the cylinder into a plurality of operating chambers. The ends of the cylinder are rotatably supported by first and second bearings (22, 26). The first bearing is secured to the casing. A drive unit (12) for rotating the cylinder and rod includes a rotor fixed to the cylinder. The rotor has the center of gravity which is apart from the middle of the cylinder in its axial direction toward the first bearing.</p>
