A method and apparatus for evaluating an ultraviolet radiation protection effect in a measurement sample is used for evaluating SPF (Sun Protection Factor). First, a temporal change of the spectral transmission spectrum in the measurement sample within a predetermined light wavelength range at predetermined wavelength intervals is measured. Second, a correlation between a light irradiating time and minimal erythema doses by predetermined lime intervals based on the temporal change of the spectral transmission spectrum is set. Third a predicted in vitro SPF in the measurement sample using a time until an accumulated minimal erythema dose that is obtained as a time integration of the minimal erythema doses based on the correlation obtained in the second step reaches 1 MED (Minimum Erythema Dose) is calculated.