To restrain abnormal sound caused by turbulence which is generated when an exhaust shutter valve is opened.

A disc-like valve element 14 which changes the passage area of an exhaust passage 12, is rotated around a valve shaft 13 so that it is inclined by a predetermined angle at a state totally closed so as to ensure small gaps 31 between swingable end parts 14a, 14b and the inner wall surface of the exhaust passage 12. Four communication holes 32 are formed in the outer peripheral part of the valve element 14 in the thickness wise direction of the latter, being located at positions having an equal radial distance from the center thereof. High speed gas streams are jetted through the communication holes 32, being directed toward the inner wall surface of the exhaust passage 12. Accordingly, turbulence caused by a gas stream flowing through one of the gaps is straightened so that exhaust gas smoothly flows, thereby it is possible to restrain occurrence of abnormal sound caused by turbulence.