Objectives: Hassaku (Citrus hassaku) contains higher levels of auraptene in its rind compared to other citrus fruits. Auraptene has been reported to potentially have various health benefits in both in vitro and in vivo studies. We conducted an exploratory study of the effects of auraptene on humans at risk of metabolic syndrome using fractions of oil squeezed from Hassaku fruits, which contain high concentrations of auraptene. Methods: The participants were 14 adult men with an abdominal circumference of 85 cm or more and low-density lipoprotein-cholesterol (LDL-C) of 140 mg/dL or more. The participants were randomly divided into 2 groups of 7 each. The test food was Hassaku oil extract in the form of soft capsules, which was administered as auraptene (10 or 20 mg/day, respectively) for 12 consecutive weeks. The participants underwent clinical examinations, physical examinations, blood and urine tests before ingestion, and at 6 weeks and 12 weeks after ingestion. Results: In the 10 mg/day group (n = 7), a significant decrease from pre-ingestion to 12 weeks after ingestion was observed as follows: Total cholesterol: 233.7 ± 34.7 mg/dL → 218.3 ± 28.4 mg/dL (p = 0.038, t-test), Insulin: 13.17 ± 4.41 → 9.76 ± 3.71 μU/mL (p = 0.022, t-test). The 20 mg/day group (n = 7) also showed the same tendency of variation, but it was not significant. Conclusions: In the 10mg/day group, the ingestion of high-auraptene Hassaku oil extract improved lipid and glucose metabolism, which suggested the contribution to the effectiveness in prophylaxis and prevention of progression of metabolic syndrome and arteriosclerosis, and suppression of glycative stress.