To provide a mechanism for restricting a turnable range of a turning body, which mechanism can restrict the turnable range within an arbitrary wide range, and can reduce noise, and further to provide an industrial robot.

An external gear 20 is fixed to the outer periphery of the output shaft 16 of a first drive motor M1. An internal gear 24 is arranged on the mounting surface 22b of a mounting substrate 22 fixed to a motor housing 12 at a predetermined distance from the external gear 20. Further, a planetary gear 30 is arranged between the external gear 20 and the internal gear 24 so as to engage with the external teeth 20a of the external gear 20 and the internal teeth 24a of the internal gear 24. In addition, an engaging projection 32 is formed on the planet gear 30, and engaging pins 36 are provided on the mounting substrate 22 so as to engage with the engaging projection 32.