Adulteration of sesame oil using near infrared (NIR) spectroscopy was determined. Vegetable oils including sesame oil were scanned on the NIR spectrophotometer at 400-2500 nm. Partial least square (PLS) was applied on the standardized full NIR spectral data. Discriminant analysis with PLS is adequate for determination of sesame oil adulteration, except with decreasing adulteration rate. Designing of quality control system, which uses NIR spectroscopy to measure adulteration level of sesame oil is thus possible, although more work is required to give acceptable accuracy level.