A radio wave absorber including a radio wave absorbing layer containing a magnetic powder and a binder, in which a metal layer is not provided, a filling rate of the magnetic powder in the radio wave absorbing layer is 35% by volume or less, and in a case where the filling rate of the magnetic powder in the radio wave absorbing layer is denoted by P % by volume and a thickness of the radio wave absorbing layer is denoted by Q mm, the following relationship is satisfied, 0.65≤(P/100)×Q, and the compound.