Abstract: A harmonic speed reduction transmission device equipped with a strain gauge, includes a motor, a harmonic reducer, and a rigid gear assembled in a housing. The motor drives the harmonic reducer to output a rotational torque of reduced speed. The rigid gear is used to guide the harmonic reducer. The rigid gear is formed with at least one bracket that can generate deformation under a bending moment, used to fix the rigid gear inside the housing. The strain gauge is attached on the bracket, used to detect the torque generated by the reduced speed output from the harmonic reducer. Through such a design, the structural configuration of the device is optimized.