To improve sealability and holding power of a holding and sealing material holding an exhaust gas treatment body, useful in an apparatus for purifying an exhaust gas, in a metal shell.

The holding and sealing material for holding an exhaust gas treatment body useful in an apparatus for purifying an exhaust gas has a first surface and a second surface, is constituted of a sheet material composed of an inorganic fiber in which the unevenness height of the second surface is lower than that of the first surface. The holding and sealing material is wound and fixed in such a way that that the second surface is brought into contact with the outer peripheral surface of the exhaust gas treatment body. Consequently, the apparatus for purifying an exhaust gas, which reduces wrinkles caused by difference in circumference between the internal circumference and external circumference of the holding and sealing material and has excellent gas sealability and retention, is obtained.