1. A state transition management device comprising: a memory which stores a state transition rule and from which a plurality of subsequent state number candidates are read out when the memory receives a first signal based on a state number as an address; a selection method specifying unit which outputs a selection method specifying signal upon reception of a second signal based on the state number; and a selection circuit which receives the selection method specifying signal read out from the selection method specifying unit, a signal based on an event, and a third signal based on the state number, and selects a subsequent state number from the plurality of subsequent number candidates.