1.Context: In recent years, Japanese women become pregnant in older age than before in Japan. Pregnant women's BMI is higher than before in Japan. hypertensive disorders of pregnancy（HDP） is increasing. Medical history of hypertension is one of the risk factors of HDP. The prevention of hypertension is important. In general adults, sodium is said to increase blood pressure, but potassium is said to decrease blood pressure. 2.Objective: To clarify wheter pregnant women know the effect of sodium and potassium to blood pressure in pregnant women or not. 3.Methods: we used semi-structured questionnaire method to pregnant women who agreed with that method at pregnancy medical examination visit. 4.Participants: Seventy-seven healthy pregnant women (32 primiparae and 45 multiparae ) 5.Intervention(s)： We did not intervate. 6.Main Outcome Measure(s)： Whether participants know the word of sodium and the effect of sodium to blood pressure or not. whether participants know the word of potassium and the effect of potassium to blood pressure or not. 7.Result(s)： Forty-four pregnant women (44/77,57.1%) know the word of sodium. Forty pregnant women (40/77,51.9%) know the effect of sodium to blood pressure. Forty-four pregnant women (10/77,13.0%) know the word of potassium. Forty pregnant women (1/77,1.2%) know the effect of potassium to blood pressure. 8.Conclusions： The effect of sodium to blood pressure is well known in pregnant women. The effect of potassium to blood pressure is not known in almost pregnant women. It is important that we give pregnant women the information the effect of potassium to blood pressure.