A bumper beam having increased bending strength achieved with a minimum increase in the weight of the bumper beam. The bumper beam (1) is mounted to the front of a vehicle, extends along a reference line (W), and is provided with a beam body (2) and a reinforcing plate (3). In at least one cross section perpendicular to the reference line (W), the reinforcing plate (3) extends linearly and the beam body (2) includes a pair of protrusions (2t, 2s) protruding, while surrounding an inner space, from the reinforcing plate (3) in a direction intersecting the reinforcing plate (3). If the Young's modulus and the density of the beam body (2) are Est and ρst, respectively, and the Young's modulus and the density of the reinforcing plate (3) are E2 and ρ2, respectively, the expression (Est/ρst3)