A component measuring device comprising a light emitting element adapted to irradiate a measurement object with irradiation light for measurement, a light receiving element adapted to detect reflected light reflected from the measurement object , and a measuring portion adapted to measure a component in a fluid impregnated into the measurement object on a basis of a detected value of the reflected light, the component measuring device comprising: a block body having a mounting portion having an opening so as to be opposed to the measurement object , and having a reflected light optical path adapted to guide the reflected light to the light receiving element , the reflected light optical path communicating with the mounting portion ; and a reflected light lens adapted to condense the reflected light onto the light receiving element , wherein the reflected light lens is formed as an aspheric lens for reducing at least spherical aberration of the reflected light on a basis of a position of disposition of the light receiving element , and is disposed on the reflected light optical path by being inserted into the mounting portion from the front side of the opening of the mounting portion , the block body has an irradiation light optical path adapted to guide the irradiation light to the measurement object , an irradiation light lens adapted to condense the irradiation light onto the measurement object is disposed on the irradiation light optical path , and the reflected light lens and the irradiation light lens are arranged so as to share a retained portion retained by the mounting portion , and molded integrally with each other, characterized in that an optical axis of the irradiation light lens and an optical axis of the reflected light lens are formed substantially in parallel with each other, and the aspheric lens is formed in a shape reducing the spherical aberration of the reflected light incident at a predetermined angle with the optical axis of the reflected light lens . a block body having a mounting portion having an opening so as to be opposed to the measurement object , and having a reflected light optical path adapted to guide the reflected light to the light receiving element , the reflected light optical path communicating with the mounting portion ; and a reflected light lens adapted to condense the reflected light onto the light receiving element , wherein the reflected light lens is formed as an aspheric lens for reducing at least spherical aberration of the reflected light on a basis of a position of disposition of the light receiving element , and is disposed on the reflected light optical path by being inserted into the mounting portion from the front side of the opening of the mounting portion , the block body has an irradiation light optical path adapted to guide the irradiation light to the measurement object , an irradiation light lens adapted to condense the irradiation light onto the measurement object is disposed on the irradiation light optical path , and the reflected light lens and the irradiation light lens are arranged so as to share a retained portion retained by the mounting portion , and molded integrally with each other, characterized in that an optical axis of the irradiation light lens and an optical axis of the reflected light lens are formed substantially in parallel with each other, and the aspheric lens is formed in a shape reducing the spherical aberration of the reflected light incident at a predetermined angle with the optical axis of the reflected light lens . <EOS>