Internally engaged planetary gear device and robot joint device

A joint device for a robot, comprising:

• the internal-meshing planetary gear device comprising:
• a bearing member, provided with an outer ring, and an inner ring arranged on an inner side of the outer ring and supported to be rotatable relative to the outer ring with a rotation axis as a center;
• an internally toothed gear, provided with internal teeth and fixed to the outer ring;
• a planetary gear, provided with external teeth partially meshing with the internal teeth;
• and
• a plurality of inner pins, configured to revolve in a plurality of inner pin holes formed in the planetary gear and configured to rotate relative to the internally toothed gear, in a state where the plurality of inner pins are inserted into the plurality of inner pin holes respectively, and
• a plurality of sets of rolling bearings configured to hold each of the plurality of inner pins at both sides of the planetary gear in a direction parallel to the rotation axis,
• wherein each of the plurality of inner pins is held on each corresponding set of rolling bearings in a self-rotatable state;
• a first member fixed to the outer ring;
• and
• a second member fixed to the inner ring.