The following procedures are included: a procedure (1) for measuring a metallic paint color by a multi-angle spectrophotometer and storing the multi-angle colorimetric value Lab* of the paint color, a color classification code to which the paint color belongs, and a computer graphic image in a memory of a computer and a procedure (2) for calling a metallic paint color to be retrieved (this is referred to as the metallic paint color concerned) from the memory by using a paint color name as a keyword. Moreover, in the case of a new color not stored in the memory, the color is measured by a multi-angle spectrophotometer and stored in the memory in accordance with the procedure (1). A screening function (3) is included which previously narrows down paint colors whose approximate colors will be computed by using color classification codes when computing an approximate color of the metallic color concerned.