Apparatus for controlling exhaust purifying catalyst of internal combustion engine

An apparatus for controlling an exhaust purifying catalyst has a high sulfur switch (84) that is switched between an on state and an off state by an occupant such as a driver according to the sulfur concentration level of the fuel used. The control procedure of sulfur poisoning elimination control for eliminating sulfur poisoning of the exhaust purifying catalyst is changed based on whether the switch is on or off. Accordingly, the sulfur poisoning elimination control is executed in a favorable manner in accordance with the amount of sulfur poisoning of the exhaust purifying catalyst.