Turbine and manufacturing method of turbine

A manufacturing method of a turbine, the method comprising the steps of:

• preparing a turbine blade wheel;
• arranging a plurality of nozzle vanes apart from each other in a circumferential direction of the turbine blade wheel on a radially outer side of the turbine blade wheel and providing the plurality of nozzle vanes in a freely rotatable manner about a rotation shaft in an axial direction of the turbine blade wheel;
• providing an annular member extending in the circumferential direction in a freely rotatable manner in conjunction with the plurality of nozzle vanes;
• and
• providing an engagement portion to the annular member, the engagement portion including a pair of sliding surfaces facing each other in the circumferential direction, a driving member rotatably driven by an actuator being slidably engaged with the pair of sliding surfaces, the engagement portion having a thickness thicker than a thickness of a peripheral portion of the annular member.