1. A light distribution characteristic measurement apparatus for measuring a light distribution characteristic of a light source, comprising: an imaging unit disposed at a predetermined distance from the light source; a movement mechanism configured to successively change a positional relation of the imaging unit with respect to the light source, while keeping the distance between the light source and the imaging unit; and a processing module configured to calculate the light distribution characteristic of the light source, based on a plurality of image data taken by the imaging unit and a relative position of the imaging unit with respect to the light source when each of the plurality of image data is taken, the processing module being configured to obtain a plurality of image data taken under a first imaging condition and a plurality of image data taken under a second imaging condition different from the first imaging condition, determine corrected image information corresponding to a relative position of interest, from first image information corresponding to the relative position of interest included in the image data taken under the first imaging condition and second image information corresponding to the relative position of interest included in the image data taken under the second imaging condition, and calculate the light distribution characteristic based on the corrected image information corresponding to the relative position of interest, the light distribution characteristic including information about the luminance for each illumination angle at each point on the light source.