Abstract: An air intake structure in a construction machine, comprising a radiator chamber, a radiator ventilating hole formed in an upper position of the radiator chamber, an air cleaner chamber formed in close proximity to the radiator chamber, an air cleaner ventilating hole formed in the ceiling surface of the air cleaner chamber, an intake duct disposed below the air cleaner ventilating hole and communicating with the radiator chamber, and an air cleaner disposed in close proximity to the ceiling surface of the air cleaner chamber at a position close to the intake duct. According to this air intake structure, not only the engine cooling efficiency can be enhanced to a satisfactory extent, but also a lower space in the air cleaner chamber can be fully utilized effectively.