The objectives of this investigation are as follows: 1) To sort out places of businesses that have to do with the discharge of offensive odor 2) To find out what generates offensive odor 3) To check the current status regarding offensive odor. The investigation is held through complete enumeration of approximately two thousand businesses concerning the SihwaㆍBanwol Industrial Complex. The local residents have directly visited related businesses and performed the following investigations: 1) General status check 2) Area source 3) Point source The investigation of offensive odor is utilized by direct olfactory method in six levels. Through this method, the followings have been established as DB: Degree of offensive odor, type of odor, preventive facility status, etc. The major characteristic of this investigation is that local residents have directly visited individual businesses and checked the status of offensive odor, which opens up a possibility of mutual settlement for the reduction of offensive odor between businesses and local residents. Businesses and local residents can share a common understanding and this means a great deal. Furthermore, it is widely expected that the investigation data can be utilized as a source for presuming the origin of offensive odor in case of civil petition.