Centrifugal compressor

A centrifugal compressor, comprising:

• an impeller;
• a main flow passage which receives the impeller and extends in a rotation axis direction of the impeller;
• an auxiliary flow passage which includes an upstream communication portion communicating to the main flow passage and a downstream communication portion communicating to the main flow passage at closer to the impeller than the upstream communication portion, and extends in a rotation direction of the impeller;
• a first opening/closing portion arranged in the auxiliary flow passage, the first opening/closing portion including a first opening hole;
• a drive unit configured to move the first opening/closing portion in the rotation direction;
• a second opening/closing portion fixed to an inner wall of the auxiliary flow passage at a position closer to the downstream communication portion with respect to the first opening/closing portion, the second opening/closing portion including a second opening hole;
• and
• a fin positioned closer to the upstream communication portion with respect to the first opening/closing portion and integrally rotatable with the first opening/closing portion, the fin including an introduction hole having a pair of first guide surfaces continuous to the first opening hole on an upstream communication portion side, a distance between the pair of first guide surfaces decreasing as moving from the upstream communication portion side to a downstream communication portion side.