Rotary table device

A rotary table device comprising:

• a rotary table including a table surface provided on one-end side in an axial direction of a rotation axis, and a recess recessed from the table surface toward the other end side in the axial direction;
• a frame configured to rotatably support the rotary table from a back side of the rotary table;
• a workpiece holder configured to hold a workpiece;
• a clamp unit fixedly disposed within the recess of the rotary table, and including a clamp mechanism configured to clamp the workpiece holder by fluid pressure;
• a shaft attached to the frame and configured to supply fluid to the clamp unit;
• a power transmission fluid passage extending from the shaft through the rotary table to inside of the clamp unit, and configured to pass fluid that is used to clamp or unclamp the workpiece holder by the clamp mechanism;
• and
• a seal mechanism configured to seal a gap between an inner wall surface of the recess of the rotary table and an outer wall surface of the clamp unit.