EXHAUST AFTER TREATMENT APPARATUS FOR INTERNAL COMBUSTION ENGINE

An exhaust after treatment apparatus for an internal combustion engine capable of suppressing excess of fuel component efficiently when it is determined that the operating state is such that the active state of the exhaust after treatment device is not maintainable. The exhaust after treatment apparatus includes a fuel supply amount setting unit 94 for setting the supply amount of the fuel component to be supplied by a fuel supplying device, a fuel supply amount calculating unit 92 for calculating a supply amount of the fuel component for temperature increasing control, and a limited fuel supply amount calculating unit 93 for reducing the fuel component. When the operating state determining unit 91 determines that the internal combustion engine is in the operating state where the active state of the exhaust after treatment device is not maintainable after the supply amount of the fuel calculated by the fuel supply amount calculating unit 92 is supplied, the fuel supply amount setting unit 94 sets the supply amount of the fuel component to the smaller one between the supply amount calculated by the fuel supply amount calculating unit 92 and the limited supply amount calculated by the limited fuel supply amount calculating unit 93.