PROBLEM TO BE SOLVED: To provide a knob mechanism that is applicable to a case cut in a palm part.SOLUTION: When a thumb folder 26 is turned around the shaft center in the direction where a thumb side link 16 comes close to the four finger side link 18, a slider shaft 36 provided in a relative position fixing part is simultaneously turned with this. A guide face in a long hole 34 of a slider 32 is pushed up by the slider shaft 36, and thereby the slider 32 is turned around the four finger side turning shaft B and the four finger side link 18 provided in the relative position fixing part is turned toward the thumb side link 16 simultaneously. Accordingly, a knob action using the thumb side link 16 and the four finger side link 18 is carried out by the internal abduction and bending of a thumb carpometacarpal joint 14.
