1. A music analysis apparatus comprising: a feature extractor configured to generate a time series of feature values from a sequence of notes which is designated as an object of analysis; and an analysis processor configured to compute an evaluation index value which indicates a probability that the designated sequence of notes is present in each of a plurality of reference music pieces by applying a probabilistic model to the time series of the feature values generated from the designated sequence of notes, the probabilistic model being generated by machine learning of the plurality of reference music pieces using time series of feature values obtained from the reference music pieces.