Power saving cannot be implemented in the adhoc mode by only the IEEE 802.11 standard. This is because communication partners mutually utilize the power save mode in the adhoc mode, and their states must always be managed. In the adhoc mode, the number of communication partners is not always one, and all stations which join a network are candidates, increasing the load of implementation. To solve this problem, a communication apparatus notifies a change to power save mode by an ATIM packet, RTS packet, or null packet. When the ATIM packet or RTS packet is transmitted, the communication apparatus can notify the partner of a change in mode regardless of whether the partner is in the power save mode. When the null packet is transmitted, the communication apparatus can rapidly notify the partner without waiting for any beacon.