An electronic certificate issuance system comprising at least one communication device, and an electronic certificate issuing device for issuing a set of an electronic certificate and a private key corresponding to the electronic certificate as a certification set for each of the at least one communication device, is provided. The electronic certificate issuing device includes a first connecting interface, an obtaining system, which is adapted to obtain a node ID assigned to each of the at least one communication device, a generating system, and a writing system. The at least one communication device includes a second connecting interface, a judging system, and an installing system.