The purpose of this study is to investigate the air permeability and water vapor permeability of polyester (fiber cushions. Those are made by thermal bonding of regular and lowermelting point fiber with blending ratios of 70/30, 60/40, 50/50 wt(%) , and these fiber cushions had different levels of controlled initial specific volume (53.33, 32.00, 22.86, 17.78 ㎤/g) by heattreatment (80, 100, 12$0^{circ}C$) with constant load. The relationship between air permeability and water vapor permeability of polyester fiber cushions by blending ratios, initial specific volume, heat treatment temperature and thickness was discussed. The results were as follows: The air permeability of fiber cushion was decreased with the increase of the sample thickness, packing density and the amount of low melting fiber, but it was increased slightly with the increase of the heat treated temperature. The air permeability and water vapor permeability of fiber cushions did not depend on the heat treated temperature but the water vapor permeability was decreased with the increase of the blending ratios and initial specific volume, however water vapor transfer resistance was increased slightly.