A device for measuring concentration of a constituent in blood includes: an irradiation unit for irradiating light toward a living body, the light having a wavelength disposed in a light absorption band of the constituent in the blood a light receiving unit for receiving light, which is reflected in the living body or transmitted through the living body and a concentration measurement unit for measuring the concentration of the constituent in the blood based on variation of light intensity of light received by the light receiving unit, the variation attributed to a pulse wave of the living body.
