A wireless terminal, comprising: a receiver configured to receive a first frame from an access point, the first frame including information to designate a plurality of wireless terminals (1, 2, 3, 4) and information concerning frequency resources which have been assigned to the plurality of wireless terminals for frequency multiplexing communication; controlling circuitry configured to control, when its own device is designated in the first frame, to perform the frequency multiplexing communication using the communication resource assigned to its own device; and a transmitter configured to transmit a second frame to the access point via the communication resource assigned to its own device in the frequency multiplexing communication, wherein the first frame has a plurality of fields to store information individually notified to the plurality of wireless terminals, category information to designate access categories of data to be transmitted by the wireless terminals are stored in the plurality of fields respectively, and the transmitter transmits the second frame including data that belongs to the access category designated to its own device, wherein the wireless terminal is arranged to perform carrier sensing for accessing into a wireless medium to acquire a transmission right when a result of carrier sensing is idle, and a length of time for the carrier sensing includes a fixed time and a random time, the fixed time is determined according to the access category of its own device, minimum and maximum contention window values CWmin and CWmax are determined according to the access category of its own device, and the random time is calculated by determining a contention window value CW in a range from the CWmin to the CWmax and by multiplying the CW by a slot time. a receiver configured to receive a first frame from an access point, the first frame including information to designate a plurality of wireless terminals (1, 2, 3, 4) and information concerning frequency resources which have been assigned to the plurality of wireless terminals for frequency multiplexing communication; controlling circuitry configured to control, when its own device is designated in the first frame, to perform the frequency multiplexing communication using the communication resource assigned to its own device; and a transmitter configured to transmit a second frame to the access point via the communication resource assigned to its own device in the frequency multiplexing communication, wherein the first frame has a plurality of fields to store information individually notified to the plurality of wireless terminals, category information to designate access categories of data to be transmitted by the wireless terminals are stored in the plurality of fields respectively, and the transmitter transmits the second frame including data that belongs to the access category designated to its own device, wherein the wireless terminal is arranged to perform carrier sensing for accessing into a wireless medium to acquire a transmission right when a result of carrier sensing is idle, and a length of time for the carrier sensing includes a fixed time and a random time, the fixed time is determined according to the access category of its own device, minimum and maximum contention window values CWmin and CWmax are determined according to the access category of its own device, and the random time is calculated by determining a contention window value CW in a range from the CWmin to the CWmax and by multiplying the CW by a slot time.