PROBLEM TO BE SOLVED: To provide a clamp device which can be attached to an object to be fixed by a simple operation. A clamp device (1) includes a fixed member (2), a movable member (3), a shaft body (4), and a first screw portion (27) provided on a first member of one of the fixed member (2) and the shaft body (4). A forward and backward direction by screwing with a second screw member 28 attached to the other second member of the fixing member 2 and the shaft body 4 and provided in a partial region in the circumferential direction around the shaft center. The shaft support mechanism 7 that supports the shaft 4 so as to be movable, and in the first member, the second screw member 28 protrudes from the first screw portion 27 toward the second screw member 28. The screwing switching mechanism 8 having a pressing portion 33 that presses the second screw member 28 in a direction away from the first screw portion 27. The first member has a screwing area in which only the first screw portion 27 is provided and a screwing release area in which the pressing portion 33 is provided in the circumferential direction around the axis. [Selection diagram] Fig. 11【課題】簡単な操作によって被固定物に取り付けることができるクランプ装置を提供することである。【解決手段】 クランプ装置１は、固定部材２と、可動部材３と、軸体４と、固定部材２及び軸体４のうちの一方の第１部材に設けられた第１ねじ部２７と、固定部材２及び軸体４のうちの他方の第２部材に取り付けられ、前記軸心を中心とする周方向の一部の領域に設けられた第２ねじ部材２８と、の螺合により進退方向に移動可能となるように軸体４を支持する軸体支持機構７と、前記第１部材において、第１ねじ部２７よりも第２ねじ部材２８に向けて突出し、第２ねじ部材２８を第１ねじ部２７から離れる方向に第２ねじ部材２８を押圧する押圧部３３を有する螺合切換機構８と、を備える。前記第１部材は、前記軸心を中心とする周方向において、第１ねじ部２７のみが設けられた螺合区域と、押圧部３３が設けられた螺合解除区域と、を有する。【選択図】図１１
