A seal structure includes a cylindrical outlet wall portion which forms an outlet passage at a downstream side of a turbine wheel and an annular shroud portion which is provided in a second nozzle ring and faces a blade portion. A proximal end portion of the outlet wall portion and a distal end portion of the shroud portion face each other with a gap interposed therebetween in an axial direction. An annular seal member is disposed at an inner peripheral portion of the gap in a radial direction. The seal member comes into contact with the proximal end portion of the outlet wall portion and the distal end portion of the shroud portion to block the gap.