It is so arranged that an encryption key can be shared with a communication apparatus that participates in a network anew, even in an ad-hoc-mode type of environment. In order to achieve this, a communication apparatus determines whether it possesses an encryption key shared with another communication apparatus and, in accordance with the result of the determination, initiates sharing process for sharing the encryption key with a first communication apparatus from the communication apparatus after the sharing process for sharing the encryption key has been initiated from the first communication apparatus.