The objective of the invention is to provide an optical product with a multilayer film held therein as a cross dichroic prism, in which the influence of an adhesive is further reduced. The cross dichroic prism is formed by putting together vertexes forming respective right angles of a first prism element 11a, a second prism element 11b, a third prism element 11c and a fourth prism element 11d made of a glass that have a shape of a right isosceles triangle right prism, and joining respective optical sides adjacent to one another among optical sides orthogonal to one another via dichroic films 12B, 12R made of multilayer films. Therein, a dichroic film is formed with the multilayer film of which the uppermost layer is a silicon oxide layer on at least one joint surface, and the joint surface and a confronted glass joint surface are joined according to an optical contact method to manufacture the cross dichroic prism 1. Accordingly, because there is no layer of an adhesive in an area effective as an optical path, it is possible to completely prevent deterioration in optical performance due to an adhesive layer. |