There is provided a crawler system and a crawler link structure which can be easily assembled and is superior in durability and provided at low cost. The crawler system comprises a crawler 2 in which pairs of opposed right and left links 1a and 1b are endlessly connected. One end of the pair of right and left links 1a and 1b are connected through a cylindrical connection part 3. Middle parts of the pair of right and left links 1a and 1b in the longitudinal direction are connected by an engaging part 4 which engages with a concave tooth 29 of concave-convex teeth 28 of a crawler sprocket 27. The pairs of right and left links 1a and 1b are endlessly connected by inserting connection pins 12 to the connection parts 3.