An adhesive layer attaining, in a single layer, both adhesiveness permitting direct attachment to a glass plate disposed on the front face of a display device and desired optical filter functions and hardly undergoing the change in spectral characteristics attributable to deterioration in a light absorbing agent, even during long-time use, particularly at high temperature under high humidity, as well as a composite filter using this adhesive layer. The adhesive layer has optical filter functions, containing a block copolymer having at least a specific triblock structure in its molecule and having a weight-average molecular weight of 50,000 or more and a molecular-weight distribution (Mw/Mn) of less than 1.5 and one or more light absorbing agents each having light absorption in a predetermined wavelength region, as well as a composite filter using this adhesive layer.