Personal box areas allocated to respective ones of individuals are provided in an image memory. Each personal box area is associated with a name and a first password or a second password if the first password has not been registered. When the content of a personal box is to be output, the first password is consulted if it has been registered. If the first password has not been registered, then the content of the personal box can be output without a password. In a case where a personal box is to be deleted, the first password is consulted if it has been registered. If the first password has not been registered, then the second password is consulted to determine whether the deletion operation is authorized.