is about 1 u00d7 10 u2212 3 as described above the series arrangement of the multi layered interferece filter 12 and the absorption filter 13 make the leak factor of the emission side filter section f em substantially into the product of the leak factor of the multi layered interferece filter 12 and that of the absorption filter 13 thus the whole of the emission side filter section f em has a leak factor in the order of 10 u2212 9 as illustrated in fig2 a the emission side filter f em is composed of the multi layered interferece filter 12 and the absorption filter 13 and the multi layered interferece filter 12 is composed of a transparent support 12 a and a multilayered interference film 12 b the multilayered interference film 12 b the transparent support 12 a and the absorption filter 13 are preferably formed in such a manner that light from the sample passes through the film 12 b the support 12 a and the filter 13 in this order as represented by an arrow for the following reason according to this order even when the transparent support 12 a or the absorption filter 13 emits fluorescence light weakened by the multilayered interference film 12 b passes through the transparent support and the absorption filter so that the fluorescence is weakened naturally it is preferred that the materials of the transparent support 12 a and the absorption filter 13 are each a material which emits.