1. A reconfigurable device, comprising: a plurality of processing elements; a main memory unit that stores plural pieces of circuit configuration information each of which is for causing each of said processing elements to realize an electronic circuit; a cache unit that caches circuit configuration information forwarded to at least one of the processing elements from the main memory unit; and a cache control unit that selects circuit configuration information which must be forwarded to each of said processing elements, and when the selected circuit configuration information is not stored in the cache unit, reads out the circuit configuration information from the main memory unit, stores the read-out circuit configuration information in the cache unit, and sends forward the circuit configuration information to the processing element from the cache unit.