A fluid compressor including a sealed case having an oil bank in which oil is held, a cylinder arranged in the sealed case, a rotation body eccentrically arranged in the cylinder, a main shaft and a sub-shaft formed at each of axial end portions of the rotation body, a spiral groove formed on a periphery thereof such that a pitch of the spiral groove gradually decreases from the sub-shaft side to the main shaft side, a spiral blade engaged with the groove such as to be able to project therefrom or retreat therein, a main bearing and a sub-bearing for eccentrically supporting the cylinder and the rotation body, and a suction hole provided in the rotation body for allowing an operation fluid having a low pressure before compression to flow from the main shaft side to the sub-shaft side so as to introduce the fluid into an inner space of the cylinder, the cylinder and the rotation body rotated relatively with each other so as to transport the operation fluid from the sub-shaft side to the main shaft side for compression.