Abstract: A measuring apparatus of a component contained in test water according to the invention can prevent a test water feed nozzle from clogging up and smoothly feed air into a combustion furnace, and further, can accurately measure in a short time carbon dioxide gas obtained from the complete combustion of an inorganic substance contained in test water. In a test water dropping unit 20 of the measuring apparatus 10, a test water dropping nozzle 21 for dropping test water into a combustion furnace 30 is provided at a top of the combustion furnace 30, and a protective pipe 23 in which this test water dropping nozzle 21 is accommodated is disposed outside the test water dropping nozzle 21. The bottom end 23a of the protective pipe 23 is extended downward from the test water dropping nozzle 21 and is formed at an acute angle, and the tip 21a of the test water dropping nozzle 21 is disposed in abutment with the inner circumferential surface 24 of the protective pipe 23.