Abstract: A microRNA detecting apparatus finds a region matching a microRNA model from a base sequence using base vector sequence data generated from inputted base sequence information of a detection processing target and a microRNA model that is a probability model of known microRNA. The base vector sequence data is a sequence of base vectors corresponding to respective bases of the base sequence. Each of the base vectors includes a parameter of a degree of evolutional conservation that is a characteristic of microRNA and parameters of a secondary structure that characterize a stable hairpin structure. Concerning the secondary structure, the base vector includes a stem parameter and a loop parameter in addition to a parameter of minimum free energy. The Hidden Markov Model is used as the microRNA model. It is possible to improve the accuracy of detection of the microRNA region on the base sequence when the base sequence information is processed by the bioinformatics technique.