A micro well array and a method of sealing liquid by using the micro well array; the micro well array, comprising a container having a plurality of independent wells disposed, therein, in array shape and a cover capable of covering the container, characterized in that the area of each well near the edge part thereof forms a projected part higher than the peripheral area thereof; the method, comprising the steps of injecting the liquid into the wells by an amount exceeding the volume of the wells after depositing to extrude the excess liquid from the wells so that air does not almost remain in the wells, whereby minute amount of specimen is allowed to react with reagent in a very small space and a fluorescence forming signals can be taken out efficiently.