PURPOSE: To improve cooler pipings as well as blasting efficiency of cool air by installing a cooler box on the ceiling above the operator's seat in a cabin with cool air blast port over the operator's seat.

CONSTITUTION: A cooler box 4 is fixed on the inside of the cabin ceiling 40 with exhaust ports 10 arranged downward on the both left and right sides of the rear bottom of the cooler box 4 and cool air blast port 45 on the upper front. The cool air blast port 45 is devised to control airing direction by a rotation system. In this way, the cooler pipings can be put through inside the cabin frame past between the ceiling panel and the roof so as to hold the pipings from being exposed and assure easy pipings. Also, the cool air can be effectively blown to an operator.