PURPOSE: To fold the excessive margin area of a ply or plies without any operational danger by a structure wherein full folding blades are set on the axis of a green case molding drum and can be expanded from the form of a cylinder smaller in diameter than a bead core and these blades are arranged laterally on the circumference.

CONSTITUTION: A carcass 20 is stuck onto the circumference of a tire molding drum 11 and an excessive margin area 20a of the carcass ply 20 turned inward in the radial direction along the side end face 11b overhung outward in the radial direction of the drum 11 is pushed against the outer face of the core 21 as a bead core 21 is put inside the side end face 11b, a bladder 14 is expanded, folding blades 1 are spread slightly, compressed air is supplied through an air inlet 5a and a cylinder 8 is advanced to the right in the drawing. In the manner that the overhung sides of the drum 11 are rubbed by the ends of the turned blades 1, the lengthwise movement of a sliding sleeve 7 is adjusted to press safely the excessive margin area to the outer face of the core beyond the most projected portion of the side end face.