1. A color conversion table generation method comprising: generating a color conversion table by estimating a device color corresponding to a color of a grid point in a set of grid points forming a color conversion table from a colorimetric value obtained by colorimetrically measuring a color of a gamut reproduced by an output device; estimating, in addition to a color of a grid point of a set of grid points which forms the color conversion table, a device color corresponding to a color other than the color of the grid point; and correcting the color conversion table by using the estimated device color corresponding to the color of the grid point and the estimated device color corresponding to the color other than the color of the grid point.