In the evaluation apparatus of the present invention, there are formed a plurality of minute channels having a cross-sectional area of not more than 1 mm.sup.2, one end of each of these channels joins in at a single meeting point and, when liquids are put into one or more of the liquid reservoirs in a higher position over any other liquid reservoir, the liquids flow down in the channels by gravity. Therefore, a scientific phenomenon, such as the diffusion of molecules, can be qualitatively observed. Furthermore, the apparatus provides a sufficient level of accuracy to enable the user to watch various phenomena involved in advanced technology, and uses no large quantity of chemicals or the like, which means little load on the environment.