Comparative study was done on the protein of gatsric juice in empty stomach of 54 persons including gastric patients and health ones by filter paper electrophoresis. The fluctuations of fractions of gastric juice by histamin stimulation were done to 29 cases of them. 1) Six fractions were found in the case of normal gastric juice, while 4-6 fractions were admitted in that of gastric patients. 2) These were Called A C(1) C(2) C(3) C(4) B counted from the order of larger mobility. 3) Fraction A has a larger mobility than human serum albumin. Fraction B moves to the negative side than human serum γ-globulin. Fractions C(1-4) show a similar mobility to human serum albumin and globulin. 4) Fraction A was highly recognized in gastric juice below pH. 3.0 but in that beyond pH. 3.0 it was not quite found. 5) The enlargment or appearance of fraction A was found in the gastric juice under pH 3.0 by histamin injection, but nothing was found in that above pH 3.0. 6) No enlargement or its appearance of fraction A was found in gastric cancer patients with gastric juice above pH 3.0. 7) The same tendency could be found in fracion B.