Provided is a structure enabling dispersion of a load that is incurred by a public key certificate issuer authority or a registration authority. The structure has an issuer authority that issues a public key certificate and registration authorities each of which receives and examines a request for issuance of a public key certificate made by an end entity, wherein the registration authorities are hierarchically structured. Each of registration authorities of a hierarchical level manages registration authorities that rank immediately below or end entities. The registration authority receives a request for issuance of a public key certificate and examines it. This means that a load each registration authority must incur for processing is dispersed. One hierarchical structure of registration authorities is formed under any of various standards which stipulates a security policy, scalability, geographical classification, functional classification, or an organization.