Joint structure and robot

A joint structure comprising:

• two joint members;
• a driving mechanism that drives the two joint members so as to rotate about a predetermined axis relative to each other;
• two seal members forming a seal between the two joint members at positions doubly surrounding the outside of a lubricant storing part in the driving mechanism;
• and
• a pressure-applying means that makes the air pressure in a space provided between the two seal members higher than the pressure of the outside air,
• wherein the seal member on the outer side is formed of an elastic material and has a cut portion at at least one circumferential position,
• the cut portion is inclined with respect to the radial direction, and
• wherein the outer seal member is attached to a fixed part of the driving mechanism by tightening the outer peripheral surface with a fastener.