PURPOSE: To keep the durability of a metal carrier for a long time by providing a desired number of communicating exhaust gas passing channels in the outflow end direction form an exhaust gas inflow end on the inner peripheral face being brought into contact with the outer periphery of a metal honeycomb body in a metal casing.

CONSTITUTION: Exhaust gas passing channels D provided in a metal casing C are provided with a straight line section D1 in parallel with gas flow in the exhaust gas flow direction F to make the inflow of exhaust gas into the channels D. Channel main body sections D2 not in parallel with the exhaust gas flow for displaying the exhaust air flow direction F continuously connected with the sections D1 are formed. Further straight line section D3 are formed in connection continuously with non-parallel sections D2 in an area of the exhaust gas outlow end section in the channels D to make the exhaust gas as a parallel flow. Four of non-parallel channel main body sections D2 are formed symmetrically, up and down, to act effectively for the prevention of exhaust of the passing gas in the unpurified state.