A turbocharger (1) is provided with a valve body (10) which is disposed in a suction flow path (C) leading from an inflow port (14) of a housing (4a) covering a turbine rotor blade (6) to a scroll part (15) and composed of a single piece or multiple divided pieces to supply a fluid (G) to the turbine rotor blade (6) with the inner surface thereof formed using a first wall surface (17) and a second wall surface (18) facing the first wall surface (17) as part thereof, extends from the upstream side to the downstream side of the flow of the fluid (G), is rotatably provided in the housing (4a) in a direction toward and away from the first wall surface (17) and the second wall surface (18), forms an upstream-side narrowed flow path (F1) with the first wall surface (17) therebetween at an end on the upstream side, and forms a downstream-side narrowed flow path (F2) with the second wall surface (18) therebeween at an end on the downstream side. The valve body (10) has a first surface (21) at the end on the upstream side, which faces the first wall surface (17), gradually approaches the first wall surface (17) from the upstream side to the downstream side and thereafter gradually goes away therefrom, and a second surface (22) which faces the second wall surface (18).