1. A mass spectrometry system that uses data obtained by MS n analyses where n is any integer equal to or greater than 3, to estimate an amino acid sequence, the mass spectrometry system comprising: a) a mass spectrometry means for obtaining mass spectrum data by performing an MS m analysis where m is any integer equal to or greater than 2, on a specimen and an MS m+1 analysis by selecting at least one of the mass spectrum peaks that is obtained from the MS m analysis as a precursor ion; b) a peak information collection means for extracting each of the peaks that appear in an MS m spectrum and each of the peaks that appear in an MS m+1 spectrum obtained by the mass spectrometry means, extracting peaks that are obtained after shifting the MS m+1 spectrum by the difference in the mass of the precursor ions when necessary, collecting mass information for ions that correspond to the peaks, and preparing peak lists by classifying the mass information into those that are determined as being the same as the terminal series of the precursor ion, those that are determined as being different from the terminal series of the precursor ion and those whose terminal series of the amino acid sequence cannot be determined; c) a peak extraction means using the mass information collected by the peak information collection means, for differentiating and categorizing peaks using criteria that are based on mass complementarity of each of the MS m spectrum and the MS m+1 spectrum or the mass commonality and complementarity of each of the MS m spectrum and the MS m+1 spectrum and determining an appearance frequency of the peaks for each category; d) an evaluation value calculation means for calculating an evaluation index value that identifies the probability of an ion that corresponds to each of the categorized peaks of being a product ion and an evaluation index value related to the terminal series of the ions, by using reliability calculated in advance for each of the categories that indicates the certainty of an ion corresponding to a peak that is included in the category of being a production, reliability information that includes the reliability related to the terminal series of the ion and the appearance frequency information for the peaks of each category obtained by the peak extraction means,; and e) a sequence estimation means for estimating the amino acid sequence of the specimen by using the mass information of the peaks differentiated by the peak extraction means and the evaluation index value of each peak obtained by the evaluation value calculation means.