Internal meshing planetary gear device and joint device for robot

The embodiment of the invention provides an internal meshing planetary gear device and a joint device for a robot, wherein loss generated when an inner pin rotates can be easily reduced. An internally engaged planetary gear device (1A) is provided with a bearing member (6A), an internal gear (2), a planetary gear (3), a plurality of inner pins (4), a plurality of sets of rolling bearings (41, 42), and a circulation path (170). The plurality of inner pins (4) rotate relative to the internal gear (2) while revolving in a plurality of inner pin holes (32) formed in the planetary gear (3), respectively, in a state of being inserted into the plurality of inner pin holes (32). The plurality of sets of rolling bearings (41, 42) respectively hold the plurality of inner pins (4) at both sides in a direction parallel to the rotating shaft (Ax1) with respect to the planetary gear (3). The circulation path (170) includes a gap between the inner peripheral surface of the inner pin hole (32) and the inner pin (4), and a raceway (404) of a rolling body (402) in the rolling bearings (41, 42). In a ring-engaged planetary gear device (1A), a lubricant is circulated through a circulation path (170).