To smoothly draw an inner mold by increasing a gap between the inner mold which is drawn and an inner surface of a concrete product even when the slender cylindrical concrete product is to be molded.

A form for the cylindrical concrete product comprises a flexible part bendable to moving walls of the inner mold having a peripheral wall in which both sides of a longitudinal opening are moving walls, opposed positions are fixed walls and a flexible part is formed between the moving walls and the fixed walls, and the blocked wall movable to block or to open the longitudinal opening. The flexible part provided at the moving wall is convexly bent. Thus, a moving angle θ of the moving walls at both sides of the fixed wall becomes large, and hence the gap between the inner mold and the inner surface of the concrete product is increased.