A control device for an internal combustion engine is provided with: a variable valve driving mechanism capable of changing a working angle of an intake valve while keeping a maximum magnitude of lift and opening timing constant; a reduction catalyst which absorbs nitrogen oxide in exhaust during lean combustion and reduces the nitrogen oxide absorbed during rich combustion; and a control unit changing, according to a load on the internal combustion engine, an amount of advance of closing of the intake valve at the time of switching to rich combustion.