The purpose of this study was to investigate effects of shoe fit and moisture permeability of a leather shoe on shoe microclimate and air exchange Three kinds of leather shoe with different fit were compared, whose ball girth were tight fitted: 1E, medium fitted: 2E, loose fitted: 3E. It was also examined the effect of water vapor permeability of a leather shoe which would affect water vapor transfer in a shoe. We compared the artificial leather with the natural leather. Subject trials were carried out with above shoes in a climatic chamber under the condition of 30℃, 65％RH. The shoe microclimate of the foot and the velocity over the opening the shoe were measured. The subject walked on a tread-mill for 20 minutes after 10 minutes' rest and repeated twice. The experimental results showed that the absolute humidity in a shoe microclimate of the natural leather was lower than one of artificial leather at all part of a foot. It indicated that the water vapor transfer of the natural leather was larger than the artificial leather. The smaller the ball girth of shoe was, the larger the magnitudes of velocity near the opening, especially at the arch of the foot. The decrease of absolute humidity during walking in the arch was larger for tight fitted 1E than for the medium fitted 2E. It seemed the bellows action during walking. This fit effect was supported by our earlier study of the bellows action [1-3].