A shake-prevention-mechanism-including gate valve comprising: a valve plate that opens and closes an opening of a valve box; a valve shaft that is connected to the valve plate; and an operation unit that performs an opening-closing operation of the valve plate with the valve shaft interposed therebetween, wherein the operation unit includes a bonnet through which the valve shaft movably extends, two air cylinders (10, 10) that are mounted on the bonnet such that the two air cylinders (10, 10) are parallel to a central axis of the valve shaft with the valve shaft put therebetween, and a connection mechanism that is interposed between the two air cylinders (10, 10), that connects rods (11, 11) of the two air cylinders (10, 10) and the valve shaft to each other, and that transmits forward and backward motion of the rods (11, 11) to the valve shaft, wherein the connection mechanism includes a base frame (20, 20) that is connected to the rods (11, 11) of the two air cylinders (10, 10), two side frames (21, 21) that are mounted on the base frame (20, 20), that are disposed between housings (13, 13) of the two air cylinders (10, 10), and that move along the housings (13, 13), and a center frame that is connected to the valve shaft, that is disposed between the two side frames (21, 21), and that moves along the side frames (21, 21), characterized in that the valve further comprises a single or plurality of shake prevention mechanisms (36A, 36B) for preventing a shake when the operation unit performs the opening-closing operation of the valve plate is disposed at at least a single facing portion among two facing portions at which outer side surfaces (21a, 21a) of the two side frames (21, 21) face respective inner side surfaces (13c, 13c) of the two housings (13, 13) and two facing portions at which inner side surfaces (21b, 21b) of the two side frames (21, 21) face respective left-hand and right-hand side surfaces (22a, 22a) of the center frame, and wherein the single or plurality of shake prevention mechanisms (36A, 36B) includes a sliding member that is disposed on a sliding surface that is formed on one of two side surfaces that face each other and on the other and a spring mechanism that presses the sliding member in a direction in which the sliding member comes into contact with the sliding surface. a valve plate that opens and closes an opening of a valve box; a valve shaft that is connected to the valve plate; and an operation unit that performs an opening-closing operation of the valve plate with the valve shaft interposed therebetween, wherein the operation unit includes a bonnet through which the valve shaft movably extends, two air cylinders (10, 10) that are mounted on the bonnet such that the two air cylinders (10, 10) are parallel to a central axis of the valve shaft with the valve shaft put therebetween, and a connection mechanism that is interposed between the two air cylinders (10, 10), that connects rods (11, 11) of the two air cylinders (10, 10) and the valve shaft to each other, and that transmits forward and backward motion of the rods (11, 11) to the valve shaft, wherein the connection mechanism includes a base frame (20, 20) that is connected to the rods (11, 11) of the two air cylinders (10, 10), two side frames (21, 21) that are mounted on the base frame (20, 20), that are disposed between housings (13, 13) of the two air cylinders (10, 10), and that move along the housings (13, 13), and a center frame that is connected to the valve shaft, that is disposed between the two side frames (21, 21), and that moves along the side frames (21, 21), characterized in that the valve further comprises a single or plurality of shake prevention mechanisms (36A, 36B) for preventing a shake when the operation unit performs the opening-closing operation of the valve plate is disposed at at least a single facing portion among two facing portions at which outer side surfaces (21a, 21a) of the two side frames (21, 21) face respective inner side surfaces (13c, 13c) of the two housings (13, 13) and two facing portions at which inner side surfaces (21b, 21b) of the two side frames (21, 21) face respective left-hand and right-hand side surfaces (22a, 22a) of the center frame, and wherein the single or plurality of shake prevention mechanisms (36A, 36B) includes a sliding member that is disposed on a sliding surface that is formed on one of two side surfaces that face each other and on the other and a spring mechanism that presses the sliding member in a direction in which the sliding member comes into contact with the sliding surface.