Every year, a large amount of by-products produced by fish processing industries is discarded or used for less profitable purposes. In this study, we will describe a technique for producing high-quality, edible oil from the viscera of yellowtail fish (Seriola quinqueradiata) which can be served as a source of omega polyunsaturated fatty acids. Yellowtail fish viscera oil was extracted using supercritical carbon dioxide (SC-CO 2) extraction and Soxhlet apparatus. SC-CO 2 extraction was carried out in a semi-batch process at a temperature and pressure ranging from 40°C to 50°C and from 15 to 30 MPa, respectively, and a CO 2 flow rate of 27 g/min for 3 hr. During the experimental study, the influence of operation parameters such as extraction time, operating pressure, and operating temperature on yield of oil was investigated.