A turbine housing assembly including a plurality of constituent members connected to one another to constitute a turbine housing into which a turbine wheel rotated by exhaust gas introduced from an engine is inserted, the turbine housing assembly at least comprising: a scroll part of a bottomed cylindrical shape that has a surrounding wall part and a bottom face part, the scroll part including: an exhaust gas flow path of a spiral shape formed inside the bottomed cylindrical shape and configured such that exhaust gas that has flowed in from an exhaust gas inlet flows through the exhaust gas flow path; and an exhaust gas outlet having a through hole formed on the bottom face part, the exhaust gas outlet being configured such that the exhaust gas that has flowed through the exhaust gas flow path flows out from the exhaust gas outlet; and a connection part connectable to a bearing housing that houses a bearing for supporting a rotation shaft of the turbine wheel, the scroll part and the connection part each being formed by processing a single piece of sheet metal and each being welded to an annular lid part that is orthogonal to a turbine axial direction, so that the scroll part and the connection part are connected to each other in the turbine axial direction via the annular lid part, characterized in that the annular lid part includes a flat plate-like part of an annular shape and positioning portions protruding outward from the flat plate-like part, the positioning portions being disposed on the positions corresponding to positioning portions of the scroll part and bushing insertion holes formed on the connection part, an end face of a threaded bushing which is inserted into each of the bushing insertion holes is connected to the positioning portion of the annular lid part, and one side of the annular lid part is welded to the scroll part and the other side of the annular lid part is welded to the connection part. an exhaust gas flow path of a spiral shape formed inside the bottomed cylindrical shape and configured such that exhaust gas that has flowed in from an exhaust gas inlet flows through the exhaust gas flow path; and an exhaust gas outlet having a through hole formed on the bottom face part, the exhaust gas outlet being configured such that the exhaust gas that has flowed through the exhaust gas flow path flows out from the exhaust gas outlet; and a connection part connectable to a bearing housing that houses a bearing for supporting a rotation shaft of the turbine wheel, the scroll part and the connection part each being formed by processing a single piece of sheet metal and each being welded to an annular lid part that is orthogonal to a turbine axial direction, so that the scroll part and the connection part are connected to each other in the turbine axial direction via the annular lid part, characterized in that the annular lid part includes a flat plate-like part of an annular shape and positioning portions protruding outward from the flat plate-like part, the positioning portions being disposed on the positions corresponding to positioning portions of the scroll part and bushing insertion holes formed on the connection part, an end face of a threaded bushing which is inserted into each of the bushing insertion holes is connected to the positioning portion of the annular lid part, and one side of the annular lid part is welded to the scroll part and the other side of the annular lid part is welded to the connection part.