To provide a catalytic device which can restrain a space where a catalyst is arranged in a flow passage or the distance of a flow passage.

This catalytic device includes a storage container 1 where a fluid to be treated is made to flow out and flow in, and a catalyst 4 which is arranged inside the storage container 1 and has a face 2 and a back 3. The storage container 1 has one surface 9 which forms an inlet 11 for the fluid to be treated so as to be opposite to the face 2 of the catalyst 4, and the other surface 10 which forms an outlet 12 for the fluid so as to be opposite to the back 3 of the catalyst 4. In addition, the catalyst 4 has a plurality of first apex parts 13 extending in one direction as kept in contact with the inner surface side of one surface 9 of the storage container 1, a plurality of second apex parts 14 extending in one direction as kept in contact with the inner surface side of the other surface 10 of the storage container 1, and an extension surface 15 extending to the first apex part 13 and the second apex part 14. Besides, a gap 21 is arranged between both end sides of the storage container 1 and the catalyst 4.