In order to facilitate rational development on the efficient new ventilation system with new detectorsagainst the health problems caused by VOC in residential buildings, authors studied to clarify the actualIAQ conditions around occupied area. To grasp the contemporary circumstances andtransfer-mechanisms of VOC in houses, the actual data regarding the pollutants and its movementwere collected in 9 detached houses in Tochigi prefecture. In this paper, investigated results for indoorthermal environment, ventilation and indoor chemical pollutants are described. In this study, aninteresting decreased trend of average concentration of formaldehyde was found. Steady appearanceof alternative chemicals such as various carbonyls, and frequent observation of unexpected TVOCvalue over 400?g/m3 are discussed. A composition ratio of VOCs and its characteristic were analyzed.The results of this research were compared with that of the past nationwide research in Japan. As aresult, comparing two constructions between Japanese conventional method and 24 method, eachcharacteristic of indoor air pollutions was identified. The characteristic of indoor chemical pollutions in 9houses in Tochigi prefecture was similar with that of the past nationwide research in Japan.