Due to its similarity to the human race, monkey is one of the most important animal for many kinds of experiments. But we have still many problems of inquiry on that animal. For example, there are a few histological and histochemical investigations on the salivary glands of the monkey. Especially, there has been no such investigations on the Japanese monkey. That is why the author has made the following study.Parotid, submandibular and sublingual glands of 4 adult Japanese monkeys were fixed in buffered formalin. The fixed pieces were embedded in paraffin and cut in 6μ thin sections.For the histological studies, the sections were stained with hematoxylin (Mayer)-eosin and azan staining. For the demonstration of neutral polysaccharide, PAS reaction, PAS-dimedon method, saliva test for glycogen, acetylation-PAS reaction, acetylation-saponification-PAS reaction, sulfation-toluidine blue (pH2.5), alcian blue (pH2.2)-PAS reaction were used and the demonstration methods for acid mucopolysaccharides were as follows: aldehyde fuchsin-alcian blue method, alcian blue-safranin method, neutral red method (Sugiyama), Ohno method for differentiation for hyaluronic acid and chondroitin sulfuric acid, alcian blue (pH2.5, pH1.0, pH0.5 pH3.0MgCl20.0-1.0mol), alcian blue (pH3.0 MgCl2 0.0-1.0mol)-PAS reaction, methylation-alcian blue (pH2.2), methylation-saponification-alcian blue (pH2.2).For the demonstration of proteins, the acrolein-Schiff method (P. VAN DUIJN) was tried. The results were as follows:1) The author could hardly find the fat cells in the parotid gland, the submandibular gland and the sublingual gland.2) The so-called serous cells in the sublingual gland are remarkably fewer than the mucous cells, and frequently formed the demilune.3) The acinar cells of the parotid gland are morphologically considered to be the serous cell, but, judging from the histocheinical staining reactions, they contain a very small quantity of neutral mucopolysaccharide, sialomucin and sulfomucin. Therefore, the author considered those cells to be the seromucous cell.4) According to the above-mentioned reasons, the so-called serous cells in the submandibular gland and the sublingual gland were also regarded as the seromucous cells.The reaction of sulfomucin in the serous cells of the sublingual gland were most distinguishable among those cells of the three glands.5) Neutral mucopolysaccaride, sialomucin and sulfomucin were also demonstrated in the mucous cells of the sublingual gland. The reaction of sulfomucin in those cells were pretty remarkable, while, the author could not get clear demonstration of this substance in the mucous cells of the submandibular gland. But the existence of neutral mucopolysaccharide and sialomucin in those cells were proved.6) All kinds of the acinar cells in the three kinds of salivary glands were proved to have no glycogen but protein.