A wireless communication system in which an access point apparatus performs simultaneous transmission to a plurality of station apparatuses (2-1, 2-K) that are associated with the access point apparatus, the wireless communication system being characterized in that: the access point apparatus comprises: a group storage unit which is configured to store an association between a station apparatus included in a group that is a target for the simultaneous transmission and group identification information; a group identification information notification unit (1-2, 1-3, 1-8) which is configured to notify each station apparatus included in the group of the group identification information; an another identification information acquisition unit (1-3, 1-5, 1-9) which is configured to acquire group identification information that is being used by another access point apparatus; and an identification information change unit which is configured, if group identification information that is being used by the access point apparatus itself overlaps with the group identification information that is being used by the other access point apparatus, to change the group identification information so as to reduce the number of pieces of overlapping group identification information, each of the station apparatuses comprises: a reception unit (2-1-2, 2-1-3, 2-K-2, 2-K-3) which is configured to receive a signal including group identification information of a group to which the station apparatus belongs; a determination unit (2-1-5, 2-K-5) which is configured to determine whether the received signal is destined for the station apparatus based on whether the received signal satisfies a predetermined condition; a notification unit (2-1-2, 2-1-4, 2-1-7, 2-K-2, 2-K-4, 2-K-7) which is configured, if the determination unit has determined that the received signal is not destined for the station apparatus, to notify the access point apparatus which performs wireless communication with the station apparatus of the fact that both the access point apparatus which performs the wireless communication with the station apparatus and the other access point apparatus are using the group identification information included in the received signal. the access point apparatus comprises: a group storage unit which is configured to store an association between a station apparatus included in a group that is a target for the simultaneous transmission and group identification information; a group identification information notification unit (1-2, 1-3, 1-8) which is configured to notify each station apparatus included in the group of the group identification information; an another identification information acquisition unit (1-3, 1-5, 1-9) which is configured to acquire group identification information that is being used by another access point apparatus; and an identification information change unit which is configured, if group identification information that is being used by the access point apparatus itself overlaps with the group identification information that is being used by the other access point apparatus, to change the group identification information so as to reduce the number of pieces of overlapping group identification information, a group storage unit which is configured to store an association between a station apparatus included in a group that is a target for the simultaneous transmission and group identification information; a group identification information notification unit (1-2, 1-3, 1-8) which is configured to notify each station apparatus included in the group of the group identification information; an another identification information acquisition unit (1-3, 1-5, 1-9) which is configured to acquire group identification information that is being used by another access point apparatus; and an identification information change unit which is configured, if group identification information that is being used by the access point apparatus itself overlaps with the group identification information that is being used by the other access point apparatus, to change the group identification information so as to reduce the number of pieces of overlapping group identification information, each of the station apparatuses comprises: a reception unit (2-1-2, 2-1-3, 2-K-2, 2-K-3) which is configured to receive a signal including group identification information of a group to which the station apparatus belongs; a determination unit (2-1-5, 2-K-5) which is configured to determine whether the received signal is destined for the station apparatus based on whether the received signal satisfies a predetermined condition; a notification unit (2-1-2, 2-1-4, 2-1-7, 2-K-2, 2-K-4, 2-K-7) which is configured, if the determination unit has determined that the received signal is not destined for the station apparatus, a reception unit (2-1-2, 2-1-3, 2-K-2, 2-K-3) which is configured to receive a signal including group identification information of a group to which the station apparatus belongs; a determination unit (2-1-5, 2-K-5) which is configured to determine whether the received signal is destined for the station apparatus based on whether the received signal satisfies a predetermined condition; a notification unit (2-1-2, 2-1-4, 2-1-7, 2-K-2, 2-K-4, 2-K-7) which is configured, if the determination unit has determined that the received signal is not destined for the station apparatus,