In term of plane structure, tower-type apartment have several disadvantages compared to flat-type apartment in the aspect of ventilation rate. Such disadvantages may not produce good indoor cooling effects with natural ventilation inside the heated apartment in hot summer days, so they may cause high energy consumption by an increase in cooling load. The purpose of this study is to investigate ways for improving the indoor thermal environment of tower-type apartment in summer by conducting quantitative evaluations of the airflow distribution in households.