We observe under single Ag nano-aggregate conditions that excitation profiles of surface-enhanced resonance Raman scattering (SERRS) vary with chances in surface plasmon resonance (SPR) bands that induce SERRS. It is demonstrated that the broadening of the envelope as well as the lower energy shift of SERRS excitation profiles come up with the lower energy shift of peak positions of SPR bands. This yields the direct evidence for the decrement of spectral overlap between the contribution of resonance and that of enhanced electromagnetic field on SERRS. (C) 2004 Elsevier B.V. All rights reserved.