Extension pipe and transport robot

An extension pipe comprising:

• a first belt including a plurality of first engagement pins provided on an upper side along the upper side and a plurality of second engagement pins provided on a lower side along the lower side;
• a second belt including a plurality of first engagement holes provided on the upper side along the upper side and a plurality of second engagement holes provided on the lower side along the lower side;
• and
• a first guide part including a spiral groove configured to spirally guide the first belt and the second belt, wherein
• the first belt and the second belt are spirally wound so that the corresponding first engagement pins engage the second engagement holes, respectively, and the corresponding second engagement pins engage the first engagement holes, respectively,
• each of the first engagement pins and each of the second engagement pins is configured to be insertable into the spiral groove, and
• a difference between a length of a first trajectory in which each of the first engagement pins moves along the spiral groove and a length of a second trajectory in which each of the second engagement pins moves along the spiral groove is less than half a circumference of the spiral groove.