A gonio-spectroradiometer and a measuring method thereof. The gonio-spectroradiometer includes a light source rotating on a light source axis, a first integrating sphere revolving around the light source with respect to a revolving axis perpendicular to the light source axis with a fixed radius and including an entrance formed in a direction to see the light source, a light intensity modulator adapted to modulate light intensity of light received through the first integrating sphere according to the rotation amount of the revolving axis, and a detector adapted to measure output light of the light intensity modulator at each wavelength.