To provide a black smoke purifying device capable of satisfactorily maintaining engine performance by pulverizing soot peeled-off pieces.

A black smoke purifying device 1 is equipped with an oxidation catalyst converter 10 carrying an oxidation catalyst on wall surfaces 13 of a plurality of cylindrical cells 12a, 12b, 12c so as to force exhaust gas 30 to pass therethrough. The oxidation catalyst converter 10 consists of a main body part 10a, a first part 10b containing a cell 12b which is provided to an upstream side of the main body part 10a and which has an opening area wider than a cell 12a of the main body part 10a has, and a second part 10c provided to an upstream side of the first part 10b. The cell 12b of the first part 10b and the cell 12c of the second part 10c are arranged so as to include an alternate part 14b.