The two-photon ionization of the He atom in the 21S state is studied in the electric dipole plus quadrupole approximation. A quadrupole resonance peak in the generalized cross section is obtained at 5043.5 \AA{}A. It is shown that for incident photons having wavelengths between 5042 and 5045 \AA{}A, the quadrupole term gives a significant contribution to the total generalized cross section.