The aim of this study was to establish the best manufacturing conditions for preparation by the direct compresison method of tablets which contain microcapsules having a minimal destruction rate of the coating wall, show the same dissolution pattern as microcapsules, and have enough mechanical strength for practical use, ant to elucidate the internal structure of the tablets under the best manufacturing conditions. Degree of destruction of the microcapsule wall was evaluated by the dissolution rate of the medicine in the microcapsules. To learn the mechanical strength of tablets, the crushing strength and friability were measured; their internal structure was analyzed by the porosity and pore size distribution.The best manufacturing conditions for the tablets were thus determined, and it was clarified by analysis of the internal structure that these conditions are markedly affected by the flowability of prescribed powders and the packing state at compression.