To provide an arranging structure of a secondary air inlet device for an engine, capable of narrowing an arranging space as an engine total unit by arranging the secondary air introducing device in the most suitable position.

In this arranging structure of a secondary air inlet device 45, supplying the outside air to exhaust gas discharged from a combustion chamber of an engine 3 to make combustion of unburnt gas, this secondary air inlet device 45 is arranged in the upper side of exhaust manifolds 29, 30 mounted in a cylinder head 19 of the engine 3.