Since the air permeabilities are closely connected with clothing hygiene, air permeabilities required to optimize dressing were studied and measured the air permeabilities that take air layers among fabrics into account. ` The thickness of air layers were controlled from 3mm to 24mm, and the numbers of air layers were made from one layer to three layers. The samples used were selected in casual wears in spring and autumn. The results obtained are as follows; 1. Specific air permeabilities of superimposed fabrics decreased gradually according to the increase of superimposed number. 2. Specific air permeabilities of the same kind of fabrics increased at first and later decreased by the increase of intervals when the fabrics are superimposed at regular intervals, and those of the different kind of fabrics decreased. 3. Specific air permeabilities of the different kind of fabrics decreased to the 18mm of total thickness in air layers and increased later.