A control method of controlling, using a distributed ledger, locking or unlocking of one or more storage units, in each of which an item is storable, includes: operating a first smart contract and one or more second smart contracts by a code, stored in the distributed ledger, being executed by a computer, the first smart contract managing the one or more second smart contracts that are in one-to-one correspondence with the one or more storage units; controlling, by each of the one or more second smart contracts, locking or unlocking of a corresponding one of the one or more storage units, the controlling being performed under the management by the first smart contract; and controlling, by the first smart contract, whether to place each of the one or more second smart contracts under the management.