This study analyzes the structure types of salmon oil to evaluate the purity of salmon oil products based on the 38 different types of imported salmon oil products distributed in the Republic of Korea. The major types of omega-3 foods in the salmon oil are ethyl ester (EE) and triglyceride (TG). If the salmon oil contained potential contaminants and was processed in order to remove it, EE type omega-3 fatty acids are found in concentration. This provides a good guide in assessing if products were made with EE type ingredients or re-esterified contaminated materials. The results of the FT-IR analysis showed significant difference in the C=O, C-O band positions in TG and EE. There were 19 TG type products and 19 EE type products. The analysis of carbon isotope ratio was performed on the types of TG and EE. There were different properties in the 19 TG type products. In one product, the carbon isotope ratio was －25.15 and the other 18 products showed －22.15～－23.96. The carbon isotope ratio of all 19 EE type products showed －21.91～－23.74. The results of the TLC analysis showed similar results with FR-IR. The re-esterified TG form was not detected in the TG type products, confirming that the TG type products contained natural salmon oil. This study aimed to provide the basic material in classifying the types of natural salmon oil and re-esterified salmon oil, by analyzing the pattern and proportion of FT-IR spectrum, carbon isotope ratio, and TLC.