This invention relates to a joint rotary shaft protector, comprising a linkage module actuated in correspondence to joint bending of a user, a plurality of stop elements movable to be abutted against and restrain the actuation range of the linkage module, thumb wheel elements respectively connected to each stop element, and limiting elements for being respectively and selectively engaged with each thumb wheel element. The linkage module actuates in multi-axis manner along with the joint bending to conform to the ergonomics when in use. To restrain the joint, the thumb wheel elements are manipulated first to drive the stop elements to displace, and the limiting elements are used to fix the thumb wheel elements. Thus, when the joint is moved, the linkage module will be driven, and the actuation of the linkage module is stopped and restrained by the stop elements, making the movement range of the joint restricted or directly fixing the joint. Accordingly, this invention achieves convenient use and operation of movement range restraint, can be fixed at any angle according to the need and conform to the ergonomics to make the use more comfortable.
