Spot cooling system used at the factory is one of the occupied zone air-conditioning, and have potential for energy conservation. The workers’ physiological and subjective responses to such environments are different from those to typical uniform thermal environments, and are far less understood for Japanese. Subjective experiments were conducted to evaluate thermal comfort of Japanese in the environment with spot cooling system, simulating a big factory. People were exposed for 90 minutes, performing walking up and down the steps in the ambient area and light work which is putting machine screws in holes and clamping them with nuts in a standing position with spot cooling. Air temperature, air volume, direction of supply air and shape of diffusers were examined. It was found the effectiveness of spot cooling system on human thermal comfort. Local body cooling was observed when the diffusers were not used. Air temperature, air volume and direction of outlet affected human comfort and fatigue. Greater thermal comfort and uniform surface body temperature were shown due to setting the diffusers.