The purpose of this study was to measure concentrations of K+, Na+, Cl－ by ionometer with check salt strip, simple salimeter and Ion-selective electrode (ISE) and compare the results of each mensuration; furthermore, the possibility of inferring the Na+ concentration from Cl－ concentration of urine and the impact of K+ on the concentration of each ion was examined. The results showed that ISE determined Na+ and Cl－ concentrations in the urine are highly interrelated (R=0.9039); in addition, concentrations of Cl－, measured with strip and ISE from urine are highly interrelated (R=0.9338). The concentration of Na+ in urine, inferred by measuring Cl－ concentration with strip, has a high relationship (R=0.8580) with the concentration of Na+ in urine, measured by ISE. The results of our study will increase awareness of Na+ intake and the utility of check salt strip, as well as the possibility of inferred Na+ concentration from measures of Cl－ concentration as a screening test for reducing sodium intake.