Method for manufacturing structural member for automobile body, and press molding device

The present invention suppresses the breakage of the edges of ridgeline part flanges (7a, 7b) and wrinkling around the roots of the ridgeline part flanges while suppressing the increase of the load on a pad when a structural member (1) made of a high-tensile steel sheet or a steel sheet with a large thickness, having an approximately groove-shaped cross-section, and having an outward continuous flange at an end is press formed. A method for manufacturing a structural member (1) includes a first step in which a molding material (16) is pressed by a pad (15, 15A, 15B, 15C, 21) and pressed against a punch (13), a portion corresponding to a flange formed at ends of a groove bottom part (2) and ridgeline parts (3a, 3b) is elevated in a direction opposite to the direction of pressing, and an intermediate molded body is formed by bending respective ends of portions to be molded into the ridgeline parts (3a, 3b) by the pad (15, 15A, 15B, 15C, 21) in the direction of pressing, and performing press molding by the punch (13) and a die (14) with at least part of each of the ends being restrained and a region other than an end of a portion to be molded into the groove bottom part (2) being unrestrained.