A widely used non-invasive measurement employing nearinfrared radiation provides valuable information in the clinical and basic medical research field. The Astrim, a portable non-invasive monitoring device recently developed, evaluates peripheral circulation as well as hemoglobin levels. The present study conducted several examinations to scrutinize the reproducibility of results, efficacy, and validity of the device. Our data demonstrated the usefulness of the non-invasive monitoring device in diverse clinical circumstances and its applicability to basic physiological and medical research fields.