PURPOSE: To improve the shape of a tire by pressing a plurality of segment bead holding members formed in a ring shape through a rubber cylindrical diaphragms on the bead of a tire carcass.

CONSTITUTION: Flanges 3, 4 are respectively secured to the end of a rotatably main shaft 1 supported in a cantilever state and to the end of a sleeve 2 axially slidably mounted at the shaft 1. A plurality of segment bead holding members 9 for radially outwardly pressing the inner edge of the bead Gb of a cylindrical tire carcass G obtained in the primary molding are provided in a ring shape in the peripheral edges of the flanges 3, 4. Thus, a cylindrical diaphragm 12 which is formed of a rubber sheet is coated over the outer peripheries of the flanges 3, 4 and the outer periphery of the members 9, and cylindrical or conical retainers 15, 15A to be engaged with the outside surface of the bead of the tire carcass G are provided at the outside.