A medical apparatus includes a laser light source for blood vessel sensing (31) configured to irradiate illumination light for detecting a blood vessel, a photodetector (33) configured to detect return light of the illumination light from a subject, an optical-characteristic processing circuit (41) configured to calculate, based on a detection result of the photodetector (33), at least one of information concerning scattering of blood cells in the blood vessel and information concerning absorption by blood in the blood vessel, a blood-vessel-characteristic determination circuit (42) configured to determine a characteristic of the blood vessel based on a calculation result of the optical-characteristic processing circuit (41), and a laser light source for guide (32) configured to perform notification based on the characteristic of the blood vessel determined by the blood-vessel-characteristic determination circuit (42).
