A robot having a shaft extending in vertical directions at an end of an arm pivoting in horizontal directions around a pivot axis parallel to the vertical directions and performing work using an end effector attached to a lower end of the shaft, the shaft having a helical groove and a longitudinal groove to enable upward and downward motion in the vertical directions and pivot around an axis of the shaft, includes a ring-shaped packing having a convex portion to engage with the longitudinal groove, fitted on the shaft, and sandwiched and fixed by a stopper portion and a collar portion in an extension direction of the shaft.