Abstract: Provided is an electrolyte analyzing device that prevents contamination caused by contacting different reagents by a suction nozzle when reagent replacement is performed. The electrolyte analyzing device includes a nozzle support part 203 coupled to a suction nozzle 6 and movable between a reagent container replacement position and a reagent suction position; a locking mechanism 301 fitted with the nozzle support part 203 moved to the reagent container replacement position and fixes the nozzle support part 203 at the reagent container replacement position; and an unlocking mechanism 302 that releases fitting of the nozzle support part 203 and the locking mechanism 301 in a power-on state. When a reagent container 101 satisfies a predetermined condition, the unlocking mechanism 302 is controlled to release the fitting between the nozzle support part 203 and the locking mechanism 301, so that the nozzle support part 203 moves to the reagent suction position.