The purpose of this research was to explore the effects of textile properties on the microclimate inside caps and on subjective wearing sensations. Physical tests on heat and moisture transfer properties of cap fabrics were conducted, as well as tests on the sensations from subjects wearing the caps. The temperature and humidity inside caps were influenced by the thickness, moisture retention properties, water absorption properties, and thermal conductivity of cap fabrics. High water absorbency property was the most important factor in lowering the temperature inside caps. Air permeability and water vapor transmission rate did not affect the microclimate. It seemed to be difficult for air or water vapors to move from the skin to the outer environment because the hair was densely packed between the skin and the cap, forming a stable air layer. Thermal sensation and thermal comfort were influenced by the thickness, water absorption properties, thermal conductivity, and Qmax of fabrics. Subjective sensations were closely related to the temperature inside caps. In the temperature range of 30 to 33°C, no change in wearing sensation was found. In the temperature range above 33°C, however, subjects started feeling uncomfortable.