A turning device provided at a joint of a robot arm, the turning device comprising: a shaft cover including a tubular wall extending in an axial direction (Da); a turning shaft inserted into an inside of the wall of the shaft cover and extending in the axial direction (Da); a bearing causing the shaft cover to support the turning shaft such that the turning shaft is rotatable about a center axis of the turning shaft; and at least one operating wire coupled to the turning shaft at the inside of the wall of the shaft cover, wherein: the shaft cover includes a guide guiding the at least one operating wire; the guide is formed to be symmetrical about a symmetry plane passing through a center axis of the shaft cover and parallel to the axial direction (Da); and each of portions of the guide which portions are located at both respective sides of the symmetry plane includes an outer peripheral portion formed on an outer surface of the wall and extending from a base end of the wall in the axial direction (Da), an inner peripheral portion formed along an inner surface of the wall and extending in a circumferential direction, and a connecting portion connecting the outer peripheral portion and the inner peripheral portion. a shaft cover including a tubular wall extending in an axial direction (Da); a turning shaft inserted into an inside of the wall of the shaft cover and extending in the axial direction (Da); a bearing causing the shaft cover to support the turning shaft such that the turning shaft is rotatable about a center axis of the turning shaft; and at least one operating wire coupled to the turning shaft at the inside of the wall of the shaft cover, wherein: the shaft cover includes a guide guiding the at least one operating wire; the guide is formed to be symmetrical about a symmetry plane passing through a center axis of the shaft cover and parallel to the axial direction (Da); and each of portions of the guide which portions are located at both respective sides of the symmetry plane includes an outer peripheral portion formed on an outer surface of the wall and extending from a base end of the wall in the axial direction (Da), an inner peripheral portion formed along an inner surface of the wall and extending in a circumferential direction, and a connecting portion connecting the outer peripheral portion and the inner peripheral portion. the shaft cover includes a guide guiding the at least one operating wire; the guide is formed to be symmetrical about a symmetry plane passing through a center axis of the shaft cover and parallel to the axial direction (Da); and each of portions of the guide which portions are located at both respective sides of the symmetry plane includes an outer peripheral portion formed on an outer surface of the wall and extending from a base end of the wall in the axial direction (Da), an inner peripheral portion formed along an inner surface of the wall and extending in a circumferential direction, and a connecting portion connecting the outer peripheral portion and the inner peripheral portion. an outer peripheral portion formed on an outer surface of the wall and extending from a base end of the wall in the axial direction (Da), an inner peripheral portion formed along an inner surface of the wall and extending in a circumferential direction, and a connecting portion connecting the outer peripheral portion and the inner peripheral portion.