A blood measuring apparatus comprising: a spectroscope; an optical system configured to irradiate a living body with excitation light from a light source, and to guide, to the spectroscope, Raman scattered light from the living body; a control unit configured to adjust an irradiation position at which the living body is irradiated with the excitation light by the optical system; and a detector configured to detect a spectrum of the Raman scattered light using light of each wavelength dispersed by the spectroscope, wherein a plurality of the spectra of scattered light detected by the detector are integrated, and numerical value information regarding a substance included in blood of the living body is measured based on an integration result, characterized in that: the blood measuring apparatus comprises a determination unit configured to perform determination processing for determining, based on a spectrum detected by the detector, whether or not the irradiation position of the excitation light with which the living body is irradiated, is a blood vessel position of the living body, and to ouput blood vessel detection information indicating a determination result to the control unit, the blood measuring apparatus is configured to irradiate the living body at a blood vessel position, the control unit is configured to adjust the irradiation position based on the received blood vessel detection information and the blood measuring apparatus is configured to detect the plurality of spectra of the scattered light at changed positions. a spectroscope; an optical system configured to irradiate a living body with excitation light from a light source, and to guide, to the spectroscope, Raman scattered light from the living body; a control unit configured to adjust an irradiation position at which the living body is irradiated with the excitation light by the optical system; and a detector configured to detect a spectrum of the Raman scattered light using light of each wavelength dispersed by the spectroscope, wherein a plurality of the spectra of scattered light detected by the detector are integrated, and numerical value information regarding a substance included in blood of the living body is measured based on an integration result, characterized in that: the blood measuring apparatus comprises a determination unit configured to perform determination processing for determining, based on a spectrum detected by the detector, whether or not the irradiation position of the excitation light with which the living body is irradiated, is a blood vessel position of the living body, and to ouput blood vessel detection information indicating a determination result to the control unit, the blood measuring apparatus is configured to irradiate the living body at a blood vessel position, the control unit is configured to adjust the irradiation position based on the received blood vessel detection information and the blood measuring apparatus is configured to detect the plurality of spectra of the scattered light at changed positions. the blood measuring apparatus comprises a determination unit configured to perform determination processing for determining, based on a spectrum detected by the detector, whether or not the irradiation position of the excitation light with which the living body is irradiated, is a blood vessel position of the living body, and to ouput blood vessel detection information indicating a determination result to the control unit, the blood measuring apparatus is configured to irradiate the living body at a blood vessel position, the control unit is configured to adjust the irradiation position based on the received blood vessel detection information and the blood measuring apparatus is configured to detect the plurality of spectra of the scattered light at changed positions.