Objective: An open-label noncontrolled study was conducted in subjects with increased oxidative stress burden to evaluate the mental and physical effects of antioxidant astaxanthin. Methods: Of 35 healthy postmenopausal women, 21 with high oxidative stress (diacron-reactive oxygen metabolites; d-ROM) were selected, and 20 (55.7±4.8 years old, BMI 22.1±3.9) were included in the study, after excluding 1 dropout. In subjects orally treated with astaxanthin (Fuji Chemical Industry) at a daily dose of 12 mg for eight weeks, Anti-Aging QOL Common Questionnaire, somatometry, hematological examination/urinalysis, oxidative stress test, and vascular function tests (cardio ankle vascular index, CAVI; ankle brachial pressure index, ABI; fingertip acceleration pulse wave; flow-mediated dilation FMD) were performed before and four and eight weeks after the start of the study. Results: After eight-week treatment with astaxanthin, significant improvement was observed in 5 of 34 physical symptoms listed in the common questionnaire, including “tired eyes”, “stiff shoulders”, “constipation”, “gray hair”, and “cold skin”, and in 3 of 21 mental symptoms, including “daily life is not enjoyable”, “difficulty in falling asleep”, and “a sense of tension”. In addition, systolic (118.0±16.4 mmHg at baseline, −4.6%, p=0.021) and diastolic blood pressure (74.1±11.7 mmHg at baseline, −6.9%, p‹0.001) significantly decreased. In the vascular function test, CAVI, fingertip acceleration pulse wave, and FMD did not change, but ABI significantly increased from 1.06±0.10 at baseline to 1.10±0.06 at Week 8 (+3.7%, p=0.030). In the oxidative stress test, d-ROM did not change, but BAP significantly increased (+4.6%, p=0.030). In biochemical examination, AST (−19.2%, p=0.044), LDH (−6.4%, p=0.006), and HbA1c (−3.2%, p‹0.001) significantly improved. Although IGF-I and insulin did not change, DHEA-s (−15.1%, p‹0.001), cortisol (−22.8%, p=0.002), and adiponectin (−14.1%, p=0.003) decreased. No serious adverse event occurred during or after the study. Conclusion: Results show that astaxanthin may enhance antioxidant capacity (increase BAP), reduce lower limb vascular resistance (increase ABI), decrease blood pressure, and improve physical symptoms in women with high oxidative stress.