The invention provides for an exterior air intake system in an engine compartment of a vehicle wherein the exterior air can be guided smoothly into an air cleaner. The engine compartment of a vehicle includes: a front-end module that is separated from an engine by a predetermined distance and that is disposed to a front end of a vehicle body; an air cleaner that is positioned near to a side of the engine; a first air duct that connects the air cleaner to the engine; and a second air duct for guiding an exterior air into the air cleaner, wherein the first end of the second air duct is connected to the air cleaner and the second end of the second air duct is positioned to a center of an upper portion of the front-end module.