To provide a tandem type catalyst converter and its manufacturing method capable of keeping the interval of catalyst carriers using a simple constitution, manufacturing easily, and embodying in a lightweight construction.

The catalyst converter W' is equipped with minor diametric portions 1a with the vessels 1 for catalyst installed at the two ends and connected with the exhaust pipe and leadout pipe of an internal combustion engine, a major diametric portion 1b positioned in the center and storing catalyst carriers 2, and a cone 1c formed in a funnel shape in such a way that the diameter varies for a short time between the minor diametric portions 1a and the major diametric portion 1b. A recess 1d in compliance with the interval of the catalyst carriers 2 is formed in the middle part of the major diametric portion 1b of a work W in cylindrical shape to serve as catalyst vessel 1. The interval of adjoining catalyst carriers 2 stored in the major diametric portion 1b is kept by the recess 1d.