A wall assembly of AV-device integrated type comprises: two columnar members; a holding member bridged between the columnar members so as to hold an AV device; and a front base board and a rear base board for covering a part between the columnar members. The holding member has: a plate member whose horizontal side portions are connected to the columnar members; a rectangular opening which is formed in the plate member and into which the AV device is to be fitted; and clamping members provided in an upper side portion and a lower side portion of the opening so as to clamp the AV device from up and down directions.