Abstract: An automatic ion concentration analyzing apparatus including a plurality of ion concentration measuring cells each having an ion selective electrode and a reference electrode; a single pair of sample suction nozzle and nozzle driving device for picking up the sample to be measured; a sample supplying device for selectively supplying the sample sucked in the nozzle to the ion concentration measuring cells; and calculation and display section, which is commonly used for calculating the ion concentration concerning samples to be measured by comparing the measurement results of electric potentials induced on the ion selective electrode and the reference electrode. In the apparatus according to the invention, although the apparatus can be made small in size, the ion concentration of the samples to be measured can be analyzed in an effective manner.