In a communication system, a first wireless communication apparatuses belonging to a communication group receives a connection request frame including a notifying security level from a second communication apparatus outside of the communication group. The first communication apparatus stores a reference security level peculiar to the communication group, which is selected from security levels depending on one of encryption methods including non-encryption and encryption strengths. In the first communication apparatus, the notifying security level is compared with the reference level, and a response frame including one of a connect rejection and a connection permission is described, is generated and transferred to the second communication apparatus. The connect rejection represents a rejection of connection to the second communication apparatus and the connection permission represents a permission of connection to the second communication apparatus.