In the field of colorimetry, metamers are color stimuli with the same tristimulus values but different spectral power distributions. In general, we perceive the metamers as the same color. However, when we observed white light source metamers consisting of a high intensity discharge lamp (HID) and a white LED, they were perceived as different color. To investigate the color appearance of these white light sources, we carried out color matching experiments. These white light sources were presented respectively as a reference stimulus. A mixture of light from a red LED, a green LED, and a blue LED was used as a matching stimulus to match its color and brightness appearance with a reference stimulus. In the case of the white LED, the chromaticity coordinates derived from trichromatic matches were distributed nearby that of the reference stimulus. On the other hand, in the case of the HID, chromaticity coordinates derived from trichromatic matches were distributed in a 700K higher color temperature area than that of the HID reference stimulus. In this paper, we discuss the cause of color mismatch between colorimetric matching with relation to the variety of color matching functions.