To protect coins given to a user as change from being taken away by the next user or another person even when the user forgets to collect the change.

An automatic certificate issuing machine performs a receiving process for delivering change to a change port as as necessary (S108) and issues a certification (S109) when the machine issues the certificate in response to request from a user. When the user forgets to collect the change, the machine locks the change (S111). When the next user is the same user while the change is locked ('YES' in S113), the machine cancels the locking state of the change (S115). When the next user is not the same user ('NO' in S113), recovers the change (S118) and cancels the locking state (S119).