Abstract: In an exhaust gas cleaning system wherein secondary air is supplied into the exhaust passage to re-burn the unburnt harmful component in the exhaust gases, a secondary air controlling apparatus for an internal combustion engine is provided. At deceleration of the vehicle, secondary air is interrupted from being fed into the exhaust passage, and is introduced into the intake passage to prevent after-burning in the exhaust cleaning system. When the ignition key is switched off, secondary air is fed into the intake passage to prevent the unburnt gas from flowing out into the exhaust passage. This effect is attained by using a valve operated in response to the negative pressure in the intake pipe to protect the exhaust gases cleaning system and to clean the exhaust gases.