A fluid compressor that ensures the discharge of water from a discharge port when water is drawn into or condensed in a pump chamber. The compressor includes a pump chamber for drawing in fluid. The pump chamber includes a bottom part located in a lower portion of the pump chamber. Two rotors arranged in the pump chamber are rotated to compress the fluid in the pump chamber. A discharge port located in the bottom part discharges the compressed fluid out of the pump chamber. The bottom part defines a guide surface formed continuously from the discharge port. The guide surface is sloped downward so that water on the guide surface moves downward to the discharge port due to gravitational force.