The absorption cross-sections in the region of the resonance structure of the 2p ionization threshold of metal films are originally measured for the total series of 3d metals from Sc to Cu. The partial 2p absorption cross-sections are found, and the integral oscillator strengths are determined. The linear dependence of the sum of oscillator strengths in the range from 0 to 80 eV above the L₃ absorption edge on the number of unfilled 3d states is established. The dependence breaks down for Cr, Fe, and Ni.