The effect of opening location on the microclimate within the garment was investigated. The vapor pressure of microclimate was determined with the vertical-plate type skin model. For quantitative comparison of the results, water vapor transporting index( $W_{Τ}$) and transmitting efficiency were used. Cotton interlock knit was selected as a specimen. It was found that the opening location had great influence on the microclimate. When the total opening size was same, the order of the rate of vapor transport was waist, armhole<neck and armhole< neck <waist and armhole<neck and waist. Water vapor transporting indices of vertical openings were 3.7~4.6 times those of horizontal ones. The effect of opening location on the microclimate was greater compared with those of opening size or number of opening. The ventilation through neck and waist happened more rapidly by chimney effect than any other openings and its $W_{Τ}$ at 10% openness was 5.6 times higher than in a closed system. The vapor transport through the neck occurred more actively than at the waist by buoyancy draft. When the ventilation was restricted to the waist opening and its openness was increased, the rate of vapor transport decreased rather than increasing. When four openings were opened and the openness increased only at the waist, the rate would increase a little. For effective ventilation through waist openness, it is necessary to open other openings simultaneously. From these results, we could infer that for optimum ventilation, the selection of opening location is very important and the neck and waist are the most desirable location.