1. An information processing apparatus that clusters an input data set, comprising: a memory to store, for each of a plurality of reference data sets that is previously clustered, a reference parameter used for clustering the reference data set, the reference parameter being a model parameter of mixture distribution; and a processor to search the memory to obtain the reference parameter of at least one reference data set that is similar to the input data set; determine an initial value of a model parameter of mixture distribution of the input data set, based on the reference parameter of the at least one reference data set; modify the initial value of the model parameter of mixture distribution of the input data set, so as to match a probability density distribution of the input data set to generate an updated initial value; and cluster the probability density distribution of the input data set on a feature space of the input data set, using the updated initial value of the model parameter of mixture distribution.