The definition of Hazardous and Noxious Substances (HNS) has been defined by the Protocol on Preparedness, Response and Co-operation to pollution Incidents by Hazardous and Noxious Substances, 2000 (OPRC-HNS Protocol). HNS can be delivered both by land and sea through international trade, but are mainly traded over the seas. Europe, North America and Eastern Asia are the main trading regions of large quantities of HNS through shipping. HNS marine trade volume in Korea is about 251 million tons, accounting for 19% of total marine trade volume. Despite the rapid growth in transport of HNS by vessel, there is a lack of HNS-specialized response systems compared to oil response systems. In this study, a risk analysis was conducted of responses to HNS spill accidents, by analysing accident cases of Hanyang Ace in Ulsan port, Korea. In addition, based on the HNS spill accident scenario, the top three most concerned substances of HNS by the Korean government were selected, and the risk assessment was performed by using the attributes of the accident scenario in terms of sea state, weather condition and accident type. From the results, we found that there were no impacts of HNS spill accidents to the residents who live away from Ulsan port, but they showed more impact to the residents who live nearby Ulsan industrial area. Since atmospheric diffusion of HNS is invisible to bare eyes, it is necessary to prepare for HNS spill accidents, as shown by the risk assessment.