Analyzes chromosomal states based on amounts of expression of genes. An example apparatus comprising: a unit for storing probability distribution of amounts of expression of genes for each chromosomal state, assuming any of the chromosomal states in which the distributions of amounts of expression are different; a unit for supplying state transition probability indicating probability in which when each of the genes arrayed on the chromosome assumes any one of the chromosomal states, a certain gene array assumes any one of the chromosomal states; an input unit for receiving an expression amount measurement value of the amount of expression for each of the genes on the chromosome; and a unit for detecting a combination of the chromosomal states maximizing a probability among those that can be assumed by the genes on the chromosome, based on the probability distribution and the state transition probability.