In the scientific phenomena evaluation device of the present invention, a plurality of elongated grooves each having a cross-sectional area of not more than 1 mm.sup.2 are formed, an end of each of the plurality of flow passages joins in at one meeting point and furthermore, a liquid absorption device is provided. Therefore, it is possible to qualitatively observe scientific phenomena, such as the dispersion phenomena of molecules. Also, accuracies sufficient for experiencing high technologies, for example, various phenomena such as the diffusion phenomenon of a liquid, heat transfer phenomenon of a liquid, mixing phenomenon of liquids and chemical reactions of a liquid that occur in this fine flow passage are obtained, consumption of chemical agents and the like is small and environmental burdens are small. Therefore, this evaluation device of scientific phenomena is appropriate as an educational tool for scientific experiments.