1. An analytical method for analyzing the structure of an ionized sample on the basis of the mass spectrometric data measured on said sample and the mass spectrometric data of dissociated ions obtained by cleaving said sample as a parent ion, wherein at least one of the thermal, chemical energetic properties of the candidates of said parent ion acquired on the basis of said mass spectrometric data is calculated to derive the structural characteristics of the parent ion candidates; in that the dissociated ions of the parent ion candidates are derived as dissociated ion candidates on the basis of the characteristics; and in that said parent ion candidates are evaluated by comparing the mass spectra of said dissociated ion candidates and said dissociated ions measured, thereby to identify said parent ion.