PROBLEM TO BE SOLVED: To provide a joint power generator capable of imparting power to a knee joint mechanism of a device, attached to a persons leg, by a small-sized configuration.SOLUTION: A knee joint mechanism 5 for connecting a femoral region frame 2 and a crural region frame 3 together includes a first link 21, a second link 22, and joint shafts 21a, 21b, 22a and 22b. A joint power generator 8 imparts joint power to the knee joint mechanism 5 via along member 32 that is connected to an outer peripheral part of the first link 21.SELECTED DRAWING: Figure 5