[Object] It is an object of the present invention to provide a knee/elbow joint assist device capable of restricting motion of a connection member and capable of preventing the connection member from drooping down.[Solving Means] One connection member 31 and the other connection member 32 are placed on a knee/elbow joint, one end of the one connection member 31 is turnably connected to the other end portion 31b of one inner arm 10b, the other end of the one connection member 31 is turnably connected to the other end 31a portion of the one outer arm 10a, one end of the other connection member 32 is turnably connected to one end portion 32b of the other inner arm 20b, the other end of the other connection member 32 is turnably connected to one end portion 32a of the other outer arm 20a, and a central portion of the one connection member 31 and a central portion of the other connection member 32 are restrained by a connection-restraining member 33.
