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 insertable, 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 an exhaust part of a tubular shape comprising a separate body separate from the scroll part, the scroll part being formed by processing a single piece of sheet metal so that, on a back face side of the bottom face part of the scroll part, a recess portion through which the trough-hole of the exhaust gas outlet is formed and a projecting portion formed by a bottom surface of the exhaust gas flow path projecting toward the back face side are formed, the projecting portion surrounding the recess portion, characterized in the recess portion of the scroll part being connected to an end portion of the exhaust part in a turbine axial direction so that the exhaust part is in communication with the exhaust gas outlet of the scroll part in a state where the end portion of the exhaust part is not in contact with the projecting portion of the scroll part and a gap (a) is formed between an outer circumferential face of the exhaust part and the projecting portion of the scroll part. 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 an exhaust part of a tubular shape comprising a separate body separate from the scroll 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 an exhaust part of a tubular shape comprising a separate body separate from the scroll part, the scroll part being formed by processing a single piece of sheet metal so that, on a back face side of the bottom face part of the scroll part, a recess portion through which the trough-hole of the exhaust gas outlet is formed and a projecting portion formed by a bottom surface of the exhaust gas flow path projecting toward the back face side are formed, the projecting portion surrounding the recess portion, characterized in the recess portion of the scroll part being connected to an end portion of the exhaust part in a turbine axial direction so that the exhaust part is in communication with the exhaust gas outlet of the scroll part in a state where the end portion of the exhaust part is not in contact with the projecting portion of the scroll part and a gap (a) is formed between an outer circumferential face of the exhaust part and the projecting portion of the scroll part.