An apparatus includes a catalytic converter on an exhaust pipe and provided with a lean NOx trap (LNT) device coated with an LNT catalyst, and a catalyzed particulate filter (CPF) coated with a catalyst. The LNT device and CPF are sequentially disposed in the catalytic converter. The CPF includes at least one inlet channel, extending in a longitudinal direction, having a first end into which fluid flows and a blocked second end; at least one outlet channel, extending in the longitudinal direction, having a blocked first end and a second end through which the fluid flows out; at least one porous wall defining a boundary between neighboring inlet and outlet channels and that extends in the longitudinal direction; and a support coated with the catalyst and located within at least one among the at least one inlet channel and the at least one outlet channel.