A state transition management device includes a memory that stores subsequent state number candidates for a current state number and a selection circuit that selects a subsequent state number from among the subsequent state number candidates that have been read out from the memory. For the state number having the subsequent state number candidates that are branch destinations of the current state number and are small in number, the memory stores the subsequent state number candidates for a plurality of current state numbers at one address in the memory that can be concurrently read out. The selection circuit selects the subsequent state number based on an event identification code (109, 110) and a current state number.