In an arbitration circuit in which a shared circuit such as a memory is used exclusively by one of a plurality of functional blocks at a time, an access reservation request is issued from one of the functional blocks, and the access request associated with the access reservation request is reserved. Thereafter, when an access request is issued from another functional block, it is determined which one of the access reservation request and the access request from these functional blocks takes precedence. For example, if the access request from the latter functional block has a low priority level, the access reservation request is selected and the circuit waits for an access request from the functional block which has issued this access reservation request. In this manner, it is possible to avoid cancellation of a once-accepted access request and waiting for a high-priority access request.