To provide an apparatus which is low-cost, whose constitution is new and which measures the loss distribution of a branch optical line and to provide a measuring method.
In a measuring apparatus, optical filters 14 whose transmission wavelengths are different from each other are arranged respectively at a branch optical line one end of which is branched into a plurality of branch optical lines 1, beams of light at different wavelengths are made incident, beams of return light are received, and the loss distribution of the branch optical lines 1 is measured individually. The apparatus is provided with a light source 11 which contains all beams of light at the transmission wavelengths, and a light receiving part 2 is provided with a means which receives light by providing a wavelength separation device 15 which separates the wavelength of the return light.