Robot wrist structure

A robot wrist structure includes a first wrist element, a second wrist element, and a third wrist element which are respectively rotatable about a first axis to a third axis; drive motors for the second and third wrist elements; and gear sets that reduce speeds of rotation of the drive motors. The gear sets respectively include a driven-side large-diameter gear that rotates the second wrist element and a driven-side small-diameter gear that rotates the third wrist element, where the driven-side large-diameter gear and the driven-side small-diameter gear are coaxially arranged so as to be rotatable about the second axis. The small-diameter gear is fixed to a drive-side bevel gear that meshes with a driven-side bevel gear fixed to the third wrist element. The second wrist element includes a first housing that is fixed to the large-diameter gear; and a second housing rotatably supports the third wrist element.