An immunological agglutination detecting apparatus including an agglutination examination plate having one or more reaction vessels each provided with a bottom face of which at least a part is slanted. A light emitting source is arranged at one side of the agglutination examination plate. A light receiver is situated on the other side thereof. Respective images of the agglutination patterns formed on the bottom faces of the reaction vessels are focussed on the light receiver through individual lenses in order to detect, by an electrical device, the agglutination patterns which are formed by the shining light from the light emitting source. In the preferred embodiment, the light emitting source is one or more rows of primary point sources, each corresponding to a particular vessel in the plate, and one or more supplementary point sources adjacent the ends of the row or rows. The intensity of the primary and supplementary light sources can be separately adjusted.