Composite member and composite-member manufacturing method

A composite member manufacturing method comprising:

• a preparation step of preparing a metal sheet shaped like a flat sheet, the metal sheet having an outer surface and an inner surface;
• a through hole forming step of forming a through hole in at least a part of a portion of the metal sheet to be subjected to bending, the through hole having an outer opening in the outer surface and an inner opening in the inner surface, the through hole opening into a fitting recess, the fitting recess having a depth less than the thickness of the metal sheet;
• a bending step of subjecting the metal sheet to bending along the inner surface such that it forms a bottom sheet part, a side wall part, and a bent portion therebetween with the outer opening disposed along an outer surface of the bottom sheet part and the sidewall part and the inner opening being disposed along the inner surface of the bent portion, the through hole being tapered with the outer opening having a diameter that is larger than the inner opening, the fitting recess extending from the inner opening on the inner surface of the bottom part and the sidewall part;
• and
• a filling step of filling the through hole with resin and molding the resin so that the resin forms a resin member joined to at least a part of the bent portion, the resin member being flush with the outer surface of the bottom sheet part and the sidewall part and not overlapping the outer surface of the bottom sheet part and the sidewall part, the resin member comprising:
• an inner resin part filled in the through hole;
• and
• an exposed resin part continuous with the inner resin part overlapping an inner surface of the bottom sheet part and the side wall part on each side of the inner opening filling the fitting recess, the exposed resin part following a contour of the inner surface of the bottom sheet part and the sidewall part such that the exposed resin part has a bottom resin part, a sidewall resin part, and a bent resin portion therebetween.