To provide a bellows manufacturing apparatus capable of precisely forming a bellows of a S shaped cross section without damaging.

The bellows manufacturing apparatus is provided with dies 13, 14 arranged in the axial direction of a tube stock 11, and a mandrel 18 inserted into the tube stock 11. The dies 13, 14 are divided in the radial direction of the tube stock 11. A mandrel 18 is provided with seal members 45, 46 to form a liquid pressure chamber 47 at an inner face side of the tube stock 11. By supplying a pressurized liquid into the liquid pressure chamber 47, part of the tube stock 11 is bulged outward, further, by approaching a second die 14 to a first die 13, a pleated wall of a S shaped cross section corresponding to forming faces of the dies 13, 14 is formed. After the pleated wall is formed and before the die 14 is opened in the radial direction, the die 14 is retreated a little in direction separating from the pleated wall. Thereafter, the die 14 is opened by a die opening/closing mechanism.