Abstract: This invention relates to connected parts of a long concrete pipe made by connectng some short concrete poles or concrete piles which are separately manufactured. Especially in case that a bending moment acts on an upper part of a concrete pipe having connected parts, in order to increase the strength of the connected part against the bending moment an annular concave part is made on the outer periphery of the joined part of end plates which are fixed to reinforcements at the ends of concrete pipes, and a reinforcing split ring is inserted into the said concave part and is welded to the said end plates.