Provided are a three-dimensional (3D) camera including a wavelength-variable light source for directly measuring transmittance and a method of measuring the transmittance. The 3D camera includes, as well as a light source, a transmission type shutter, and an image sensor, and a wavelength-variable light source capable of irradiating a light with a variable wavelength without being thermally affected by the light source, the image sensor, and the transmission type shutter. The wavelength-variable light source may directly measure a change in transmittance by irradiating light toward the transmission type shutter while the 3D camera operates.