A brush seal assembly may include a packing body that includes an insertion groove formed inward in a circumferential direction. The insertion groove may be positioned between a rotating body and a fixed body. The packing body may include insertion holes having openings disposed toward the insertion groove at different positions and in different directions. A brush seal part includes a brush and a support member that supports the brush. The brush may extend toward the rotating body when brush is disposed in the insertion groove. A thermal expansion member may adhere to a side of the support member and thermally expand in a circumferential direction of the packing body. Fixing members may be inserted into the insertion holes, respectively, from an outside of the packing body to maintain a fixed state of the brush seal part in radial and circumferential directions of the packing body.