The present invention is designed so that, when a plurality of inter-terminal discovery signals with varying numbers of information bits are used in a radio communication system in which inter-terminal communication is carried out, user terminals can be discovered based on the inter-terminal discovery signals. According to the inter-terminal communication method of the present invention, a user terminal (#1) determines the signal format of a discovery signal based on the number of information bits of the discovery signal,transmits the discovery signal based on the signal format, and also transmits signal format information to represent this signal format. A user terminal (#2) receives the signal format information from the user terminal (#1), and, based on the signal format represented by the signal format information, detects the discovery signal.