PURPOSE: To reduce the size of the titled concentration analyzing device by storing a sample liquid intake nozzle in a cylindrical container having a notched part, and taking the intake nozzle out of the cylindrical container during sample liquid suction and cleaning the intake nozzle in the cylindrical container during cleaning operation.

CONSTITUTION: The sample suction nozzle 1 is stored in the cylindrical container 2 having the notched part 2a. When a sample is sucked, the nozzle 1 is taken out of the container to a dotted-line position through the notched part 2a and then the sample (blood, etc.,) is sucked. The sample liquid is sucked by a pump 4 and put in a measuring electrode 5 to take a measurement 6. The nozzle 1 is returned into the container 2 after the measuring operation and a cleaning solvent is sent from a container 9 to the container 2 by a pump 13. The outside of the nozzle 1 is cleaned with the cleaning solvent, which is received by a liquid reception part 3 and then sucked by a pump 4, cleaning the nozzle 1 and the inside of the measuring electrode 5. Therefore, the internal and external surfaces of the nozzle are easily cleaned with the simple structure and reliable measuring operation is performed.