To assure a sufficient surface pressure necessary for stably maintaining a purification unit while avoiding the risk of damage to the purification unit and of rupture of a mat in an exhaust emission control device adopting an insert type metal shell structure.

A catalytic converter as this exhaust emission control device comprises a metal shell 1, a catalytic carrier 2 as the purification unit, and the mat 3 disposed between both thereof 1 and 2. In this catalytic converter, after the catalytic carrier 2 having the mat 3 wound thereon is inserted into the cylindrical metal shell 1, the outer peripheral surface of the metal shell 1 is uniformly pressurized in radial inner direction with the metal shell 1 heated by using a chuck mechanism 10 with a heating means 12 to compress the metal shell 1 to a target diameter smaller than the initial diameter thereof so as to stably hold the catalytic carrier 2 and the mat 3 in the metal shell 1.