To obtain a stable sealing function capable of being employed to a small type supercharger.

A plurality of nozzle vanes 16 are arranged in an annular flow path 10 formed in the opposite surface part between a turbine housing 1 and a turbine shroud 9. A recessed part 20 is formed in the annular flow path forming the surface part of the turbine housing 1, and a clearance control plate 21 is disposed to the recessed part 20 so that a clearance C between nozzle vanes 16 is kept constant. Two gaskets 25 the single side of which is formed into a bead shape, are disposed to a gap at the back face side of the clearance control pate 21 while being piled up with each other in such way that the outer circumferential peripheral parts of the gaskets are mutually parted in the opposite directions.