A beam is an H-shaped steel having flange parts above and under a web part. A through hole is formed on web part to let pipes and the like pass through. A ring beam reinforcing metallic material is disposed through hole. A beam reinforcing metallic material is disposed along the upper and lower flange parts at positions away from the through hole. The beam reinforcing metallic material on the front surface of the web part (opposite side of a flange of the ring beam reinforcing metallic material). The beam reinforcing metallic material in a direction in which a counter-flange surface of the beam reinforcing metallic material faces the flange part. A contacting surface is in contact with web part and is fixed to the web part with a welded section. At this time, the welded section is formed up to the height to which an angle varying part is covered.