A centrifugal compressor comprises: an impeller; an inlet pipe portion forming an intake passage to introduce air to the impeller; and a throttle mechanism capable of reducing a flow passage area of the intake passage upstream of the impeller. The throttle mechanism includes an annular portion configured to move between a first position and a second position upstream of the first position in an axial direction of the impeller. In a cross-section along a rotational axis of the impeller, an outer peripheral surface of the annular portion is formed to smoothly connect a leading edge and a trailing edge of the annular portion.