PROBLEM TO BE SOLVED: To provide a pillow position retaining device and an otolaryngologic treatment chair which operate connected arms individually and stop motions of the arms simultaneously and which thereby can arrange a pillow part at an arbitrary position.SOLUTION: A pillow position retaining device 10 is configured to include: a pillow 2 movable with respect to a back rest 1 of a chair； a movable first arm 11 connected to the back rest 1 side； a movable second arm 12 connected to the movable first arm 11 and connected to the pillow 2； a first lock 27 for stopping motions of the movable first arm 11； a second lock 28 for stopping motions of the movable second arm 12； an eccentric shaft 42 for interlocking the first lock 27 and the second lock 28 simultaneously； and a cylinder 44 for interlocking the eccentric shaft 42.SELECTED DRAWING: Figure 4
