In P2P networks, there are attacks known as Sybil attacks, where malicious users attempt to gain control over the network by using multiple nodes. To inhibit Sybil attacks, it is effective to set limits on the number of nodes per user. A decentralized authentication method, referred to as self-registration, in which the rule of majority is used to set a limit on the number of nodes in DHT (Distributed Hash Table) networks, has been proposed. However, self-registration is not effective against increasing the number is malicious users. In this paper, we propose a more reliable method by applying a local trust mechanism (SRJE, Self-Registration with Judgement Evaluation), which uses an original surveillance mechanism for self-registration. We show the effectiveness of SRJE by performing simulations comparing SRJE with self-registration.