A structural member (10) includes: a hat member (1); and a closing plate (2). The hat member (1) includes: a top-surface portion (1a); a pair of side walls (1b) extending from both edges of the top-surface portion (1a); and flanges (1c). The closing plate (2) is in contact with the flanges (1c). Each of the side walls (1b) includes a low-strength portion (1s) extending from a first edge of the side wall (1b) to a position at a distance Sh. The distance Sh is 20 to 40 % of the height H of the side wall (1b). The yield strength of the low-strength portion (1s) is 60 to 85 % of the yield strength of the side wall (1b) as measured at a position (1mid) of one-half of the height of the side wall (1b).