An exhaust gas purifying apparatus includes an exhaust gas treating body, a metal casing, and a holding sealing material. The exhaust gas treating body has a longitudinal direction and includes cell walls extending along the longitudinal direction to define cells between the cells. The metal casing has an inner surface and houses the exhaust gas treating body to face the inner surface. The holding sealing material is provided between the exhaust gas treating body and the inner surface of the metal casing to hold the exhaust gas treating body in the metal casing. The holding sealing material includes an inorganic fiber aggregated body. The metal casing has a corrosion area at least on a part of the inner surface. The corrosion area includes a corroded base material of the metal casing.