An analysis of published data on variability of the blazar 3C 345 in the optical (B, V, R) and near-IR (J, H, K) regions in the 1991-92 brightness increase has been carried out. The relative spectral energy distribution of variable sources in both regions is shown to be unchanged irrespective of flux level. Combining these spectra to a single one shows that the same source is responsible for the variability in both regions. The combined spectrum is represented quite well by the spectrum of homogeneous synchrotron source. In the near-IR the observed spectra have the same slope as the spectrum of the variable source irrespective of flux level (i.e. the variable source is the main contributor to the observed flux even at the lowest flux level). In the optical region this is the case only for the spectra at high flux level. In minimum the contribution of the constant component is considerable. All these properties are the same as in the 1983-84 brightness increase of 3C 345 (see Paper I). The only difference is the spectral index of the variable source spectrum (in 1983-84 the spectrum was appreciably steeper).