A communication apparatus, comprising: determination means for determining a timing of a period when communications with a plurality of other communication apparatuses (102a, 102b) that belong to a communication group of communication apparatuses are possible, wherein said communication group of communication apparatuses includes a plurality of other communication apparatuses having mutually synchronized periods in which communications are possible, based on a beacon signal that was transmitted from at least one of the communication apparatuses of said communication group and received by the communication apparatus in a predetermined period; transmission means for transmitting a request signal that requests obtaining of identification information in a broadcast to the plurality of other communication apparatuses of said communication group, according to the timing that was determined by the determination means; reception means for receiving response signals (706, 707) from the plurality of other communication apparatuses of said communication group transmitted in response to the transmission of said request signal; and obtaining means for obtaining identification information from each of the response signals received by the reception means from the plurality of other communication apparatuses of said communication group in a case where the request signal was transmitted by the transmission means; wherein the transmission means transmits, based on the identification information obtained by the obtaining means, a message including message information to another communication apparatus included in the plurality of other communication apparatuses that have transmitted the response signal at a timing determined by the determination means when communication with the another communication apparatus is possible and in response to a user of the communication apparatus instructing the transmission of the message, wherein, in a case where the message information includes image data, the communication apparatus is adapted to construct a Wi-Fi Direct or Infra BSS network to perform the transmission to the another communication apparatus. determination means for determining a timing of a period when communications with a plurality of other communication apparatuses (102a, 102b) that belong to a communication group of communication apparatuses are possible, wherein said communication group of communication apparatuses includes a plurality of other communication apparatuses having mutually synchronized periods in which communications are possible, based on a beacon signal that was transmitted from at least one of the communication apparatuses of said communication group and received by the communication apparatus in a predetermined period; transmission means for transmitting a request signal that requests obtaining of identification information in a broadcast to the plurality of other communication apparatuses of said communication group, according to the timing that was determined by the determination means; reception means for receiving response signals (706, 707) from the plurality of other communication apparatuses of said communication group transmitted in response to the transmission of said request signal; and obtaining means for obtaining identification information from each of the response signals received by the reception means from the plurality of other communication apparatuses of said communication group in a case where the request signal was transmitted by the transmission means; wherein the transmission means transmits, based on the identification information obtained by the obtaining means, a message including message information to another communication apparatus included in the plurality of other communication apparatuses that have transmitted the response signal at a timing determined by the determination means when communication with the another communication apparatus is possible and in response to a user of the communication apparatus instructing the transmission of the message, wherein, in a case where the message information includes image data, the communication apparatus is adapted to construct a Wi-Fi Direct or Infra BSS network to perform the transmission to the another communication apparatus.