A communication method for use in a communication system including a plurality of communication devices (2-1...2-5), the communication method comprising: a first communication device (2-1...2-5) of the plurality of communication devices (2-1...2-5) transmitting within a predefined period a connection request signal requesting a connection with another communication device (2-1...2-5) of the plurality of communication devices (2-1...2-5); a second communication device (2-1...2-5) of the plurality of communication devices (2-1...2-5) transmitting a connection permit signal which contains the number of connection request signals received during the predefined period as the number of requesting candidates indicating the number of signals likely to contend at the second communication device (2-1...2-5); the first communication device (2-1...2-5) obtaining a transmission probability defining the probability of signal transmission such that the transmission probability decreases as the number of requesting candidates contained in the connection permit signal received from the second communication device (2-1...2-5) increases, wherein the first communication device (2-1...2-5) determines the transmission probability based on the smallest of the numbers of requesting candidates contained in the respective connection permit signals when the first communication device (2-1...2-5) has received a plurality of the connection permit signals from a plurality of the second communication devices (2-1...2-5); and the first communication device (2-1...2-5) making a decision as to whether or not to transmit a signal out in accordance with the transmission probability at the timing that the signal can be transmitted to the second communication device (2-1....2-5), wherein, when the first communication device (2-1...2-5) has received the plurality of the connection permit signals from the plurality of the second communication devices (2-1...2-5), the first communication device (2-1...2-5) making a decision as to whether or not to transmit the signal out includes making a decision as to whether or not to transmit the signal out at the timing that the signal can be transmitted to the second communication device (2-1...2-5) corresponding to the smallest number of requesting candidates. a first communication device (2-1...2-5) of the plurality of communication devices (2-1...2-5) transmitting within a predefined period a connection request signal requesting a connection with another communication device (2-1...2-5) of the plurality of communication devices (2-1...2-5); a second communication device (2-1...2-5) of the plurality of communication devices (2-1...2-5) transmitting a connection permit signal which contains the number of connection request signals received during the predefined period as the number of requesting candidates indicating the number of signals likely to contend at the second communication device (2-1...2-5); the first communication device (2-1...2-5) obtaining a transmission probability defining the probability of signal transmission such that the transmission probability decreases as the number of requesting candidates contained in the connection permit signal received from the second communication device (2-1...2-5) increases, wherein the first communication device (2-1...2-5) determines the transmission probability based on the smallest of the numbers of requesting candidates contained in the respective connection permit signals when the first communication device (2-1...2-5) has received a plurality of the connection permit signals from a plurality of the second communication devices (2-1...2-5); and the first communication device (2-1...2-5) making a decision as to whether or not to transmit a signal out in accordance with the transmission probability at the timing that the signal can be transmitted to the second communication device (2-1....2-5), wherein, when the first communication device (2-1...2-5) has received the plurality of the connection permit signals from the plurality of the second communication devices (2-1...2-5), the first communication device (2-1...2-5) making a decision as to whether or not to transmit the signal out includes making a decision as to whether or not to transmit the signal out at the timing that the signal can be transmitted to the second communication device (2-1...2-5) corresponding to the smallest number of requesting candidates.