In order to study the theoretical patterns of the panel D-15 test for congenital dichromatic color vision defects, the spectral reflectance for the 16 color caps of the panel D-15 test was measured with a spectro-photometer. Then, the chromaticity-coordinates of each color cap were calculated using the spectral distribution of standard illuminant C. The theoretical patterns of the panel D-15 test for dichromats were obtained based on the confusion lines. For this procedure, the slope of the line between the color cap and the convergence point on the CIE chromaticity diagram was obtained first. Then, the order of the arrangement was decided starting with the slope having the smallest cap number and continuing progressively. For the chromaticity coordinates of the convergence points the following values were used; x = 0.7465, y = 0.2535 for protanopia, x = 1.08, y = -0.08, x = 1.40, y = -0.40, and x = 1.70, y = -0.70 for deuteranopia, and x = 0.171, y = 0.000 for tritanopia. The results show a very clear similarity between the orientation axis obtained by simulation and the actual data. Therefore, it was confirmed that dichromats arrange the color caps in the order of the slope of the line between the color cap and the convergence point, when performing the panel D-15 test. Furthermore, it was suggested that the patterns of the panel D-15 test differ by the convergence points among dichromats even of the same type.