A catalyst unit may include a carrier, a channel opening portion through which exhaust gas passes, a skin portion that is formed along a circumference and integrally formed with the channel opening portion, and a skin addition portion that is formed with a second thickness on an outside surface of the skin portion. A fabrication device of the catalyst unit may include a container, a masking member, and an elastic member, wherein plugging material flows through opened channels and does not contact the masking member. A manufacturing method of the catalyst unit may include covering the masking member and inserting plugging material into an opened channel. A channel corresponding to a dead zone is plugged and the catalyst coating layer is not formed in the plugged channels, thus reducing the cost of the catalyst.