To provide an exhaust gas cleaning apparatus that hinders displacement of the position of the accommodated matters and gas leakage attributable to weather-corrosion, and further that is easy to manufacture.

The exhaust gas cleaning apparatus is equipped with a casing 8, a mat-state thermal insulator 10 and a ceramic honeycomb filter 9. The casing 8 with tubular form is provided intermediately on exhaust pipes 6, 7 of an internal combustion engine 2, through which pipes exhaust gas is capable of being passed. The honeycomb filter 9 is housed within the casing 8 with the mat-state thermal insulator 10 wound around its outer periphery 9c. The casing 8 is provided with narrowed parts 21, 22 and a non-narrowed part 23. The narrowed parts 21, 22 are disposed at positions corresponding respectively to the end part of gas inflow side 10a and the end part of gas outflow side 10b of the mat-state thermal insulator 10. The non-narrowed part 23 is disposed at a position between both the narrowed parts 21 and 22.