To provide an economical chain for a transport line, immediately determining a wrong mounting attitude of a bearing piece body, simple in structure, simplifying assembling, disassembling and repairing, having excellent durability, easily mass-produced, and reducing the cost.

A piece body mounting space is formed in a curved peripheral wall of a projecting head 1 of a chain base A, the curved peripheral wall is provided with a lower opening part and a rear opening part, a tapered curved recessed surface 5 gradually increased in diameter as it goes downward is provided on the surface of the inner periphery of the curved peripheral wall, and a tapered curved projecting surface 13 gradually increased in diameter as it goes downward is provided on the surface of the outer periphery of the bearing piece body B. A wrong mounting inhibit projection 11 is projected on the rear face upper part of the bearing piece body B. In inserting and mounting the bearing piece body B from the lower opening part, when the mounting attitude of the bearing piece body is wrong, the wrong mounting inhibit projection 11 or the tapered curved projecting surface 13 and the tapered curved recessed surface 5 disable the bearing piece body B from being inserted in the lower opening part of the curved peripheral wall.