A medical apparatus includes a laser light source for blood vessel sensing configured to irradiate illumination light for detecting a blood vessel, a photodetector configured to detect return light of the illumination light, an optical-characteristic processing circuit configured to calculate, based on a detection result of the return light, at least one of information concerning scattering of blood cells in the blood vessel and information concerning absorption by blood, a blood-vessel-characteristic determination circuit configured to determine a characteristic of the blood vessel based on an optical characteristic calculation result, and a laser light source for guide configured to irradiate, based on the determined characteristic of the blood vessel, notification light on an irradiation near region including an irradiation region.
