A paired comparison psychophysical experiment was conducted to investigate the perception of chromatic noise. Interestingly, chromatic noise on a grey patch was less visible than on chromatic patches. Among chromatic patches, chromatic noise on a purple patch was the most visible and chromatic noise on orange, yellow, or green patch was less visible. Then a heterochromatic brightness matching experiment was conducted and it was suggested that this perception of chromatic noise could be explained by the Helmholtz-Kohlrausch effect. The gradient of the luminance of the same brightness was shown to have a correlation with the chromatic noise visibility. Thus the chromatic noise was perceived not only as chromatic noise but also as brightness noise that should be more sensitive for the human vision. Due to the dependency of the Helmholtz-Kohlrausch effect on hue and chroma, the visibility of chromatic noise should depend on the colors of the patches.