1. The absorption maxima at 593, 590 and 588 mμ were observed on the coloration by the N/100 caustic soda solution at the pH 7.5 after the addition of bromsuplhalein into human serum albumin, blood plasma and serum. 2. The combined rate of bromsulphalein with albumin was conversely increased with the decrease of bromsulphalein density on the combination of human serum protein and bromsulphalein by the utilization of paper electrophoresis and the rate of wondering pigment was gradually decreased, but the rate of residual scanty bromsulphalein combined with globulin or attached in the filter paper was almost fixed. 3. Observing the influence to the combination of serum albumin and bromsulphasein on the change of various buffer used for the paper electrophoresis, the combination was obstructed in order of veronal soda, hydrochloric acid, primary potassium phosphate, secondary natrium phosphate, borax, boric acid and veronal soda buffer. 4. Observing the influence to the combination of serum albumin and bromsulphalein on the change of pH after the addtion of buffer into normal human and dilutied serum with distilled water, the combination of them were rapidly dcreased around the pH 8-9 and it became almost zero around the pH 12. 5. In the previous experiment, the combination was more decreased with the addition of urea, lactic acid or uric acid in each than without their addition, but it showed the fixed combination by the kind of buffer on the addition of urea. the extremely scanty decline of combination on the addition of lactic acid and the considerably remarkable decline of combination. 6. Sodium chloride gave no influence of the combination of albumin and bromsulphalein in the serum of same pH, potassium chloride acted to increase the combination, and calcium chloride acted to bromsulphalein itself and acted to control the coloration by caustic soda.