To provide a molding drum of a tire member which can keep circularity even when expanding/contracting the diameter of segments.

This molding drum 1 of a tire member is for molding a ring-shaped tire member by winding a tire material around the outer peripheral surface O of a nearly cylindrical drum, and comprises a rotatably supported center shaft, a plurality of segments 7 arranged around the center shaft and constituting the outer peripheral surface of the drum and a segment moving means for expansively/contractively moving the segments 7 in the radial direction of the drum. Each segment 7 comprises a main segment piece 8 moving in the radial direction of the drum by the segment moving means, and inflective segment pieces 9 pivoted like a cantilever at one side edge 8a in the circumferential direction of the main segment piece 8 and inflectively around the axial line along the drum shaft direction. The end part of free end 9f side of each inflective segment piece 9 is loaded on the outer surface of the main segment piece 8 of another segment adjacent at the free end side, and an energizing means 10 for energizing the inflective segment piece 9 to the radially inner direction of the drum is provided.