In a valve device for a turbine of an exhaust gas turbocharger having a valve element for adjusting the pressure of the charge air supplied to, and pressurized by, the exhaust gas turbocharger, wherein the valve element is mounted on a shaft which is rotatably supported at a first bearing point on a housing element so that the valve element can be pivoted about an axis of rotation relative to the housing element by an actuating element connected to the shaft adjacent the housing element, the shaft is further supported at a second bearing point which is spaced from the first bearing point and disposed at the side of the actuating element remote from the housing element.