To provide a centrifugal separation apparatus which promotes a separation efficiency, miniaturization of the apparatus and simplification of a structure, and also is suitable as an oil separation apparatus of a compressor.

The centrifugal separation apparatus gives a revolving flow to a multiphase fluid flowed from an inlet hole formed on the side wall of a separation room to separate it into a high-density fluid and a lower-density fluid than the high-density fluid, make the separated lower-density fluid flow out of an outlet hole arranged upward the inlet hole and make the separated the high-density fluid flow out of the outlet hole arranged downward the inlet hole, wherein at least a part of the separation room is formed at a diameter-enlarging part to be gradually diameter-enlarged toward the downward side.