The vascular reflex between the blood vessels of one hand and the blood vessels of the other hand was studied. 68 subjects, 56 female college students whose ages were nineteen and twenty and 12 staff members at a college whose ages were twenty-four to sixty-eight, were tested for this experiment. In the study those 68 subjects' skin temperatures at their middle fingers of the both hands were recorded every 10 or 20 seconds for 15 minutes after they had immersed their left hands in the 5°C water. And the following results were obtainted: 1) The skin temperatures of the middle fingers of the left hands which were kept in the cold water dropped very rapidly right after they were immersed in the cold water, however, the skin temperatures started going up after about three minutes and forty seconds even though the left hands were still in the cold water. And about 10 minutes after the left hands had been moved out of the cold water, the skin temperatures of the middle fingers regained their normal levels. 2) Three distinctive types of the skin temperature change, decreasing type, increasing type and stable type, were observed at the right hand fingers of the 68 subjects which were not immersed in the cold water. The decreasing types, which showed a skin temperature drop at the right finger when the left hand was immersed in the cold water, were found 83.5% of the all subjects. The average of the skin temperature drops was 1.6°C. The increasing types, which showed a skin temperature rise at the right finger when the left hand was immersed in the cold water, were found 8.8% of the all subjects. The average of the skin temperature rises was 1.5°C. The decreasing types are related to the contration of the blood vessels and the increasing types are related to the dilatation of the blood vessels ' by the vascular reflex of the human bodies. The stable types, which showed no skin temperature change at the right finger, were found 7.3% of the all subjects.