1. A method for measuring a cholesterol content of a chicken egg comprising: irradiating the chicken egg with light in the visible to near-infrared wavelength range; detecting light radiated from the chicken egg caused by the irradiated light being transmitted through the chicken egg or reflected inside the chicken egg; acquiring a near-infrared spectrum of the light detected; and determining a cholesterol content of the chicken egg on the basis of the near-infrared spectrum acquired with the use of a calibration curve, wherein the irradiated light is irradiated to the chicken egg positioned so as to align a plane containing a long-axis line connecting the rounded end of the egg to the pointed end of the egg to be parallel to a horizontal plane, in a direction orthogonal to the long-axis line, so that the light is passed through an egg yolk of the chicken egg on a plane parallel to the horizontal plane containing the long-axis line, and the detected light is the light radiated in a downward direction from the chicken egg caused by the light transmitted through the chicken egg positioned so as to align a plane containing a long-axis line connecting the rounded end of the egg to the pointed end of the egg to be parallel to the horizontal plane, and the light being radiated in a direction orthogonal to the long-axis line so as to be passed through the egg yolk of the chicken egg on a plane parallel to the vertical plane containing the long-axis line.