Provided is a force transmitting member having a high rigidity without increasing the weight thereof. The force transmitting member (torque transmitting arm 6) for transmitting a force of a power actuator (rotary actuator 4) mounted on an outer side of a lower limb joint to a lower limb part (femoral region T) of a user provides an assist or resistive force to the lower limb. In particular, the force transmitting member comprises a pair of bifurcated portions (bifurcated portions 6c) that are bifurcated from a portion opposing a side of the lower limb obliquely in the forward and rearward directions, respectively, and the bifurcated portions are integrally formed with parts opposing an outer side face, front face and rear face of the lower limb part, respectively. The free end portion of each part opposing the corresponding part of the lower limb part is provided with a joint for a plate (plate 7) that engages the corresponding lower limb part.