Total organic carbon measuring device

A together with used which can maintain the high-speed measurement as a gas permeable membrane of the carbon dioxide separation part, suppress the influence of interfering components. And organic oxidizing unit A by oxidizing the organic matter supplied sample water into carbon dioxide, a carbon dioxide separation unit for transmitting the sample water of carbon dioxide through the organic oxidizing unit to the measurement water, the carbon dioxide separation the conductivity of the sample water from the parts and a conductivity measurement part for measuring. Carbon dioxide separation part sample water channel in which the sample water through the organic matter oxidation unit flows, an intermediate water part in which the intermediate water is present in the neutral region having a higher pH value than the sample water flowing through the sample water channel, and deionized comprising a measurement water channel measurement water composed of water flows through, between the measurement water channel and between the intermediate water part of the sample water channel and the intermediate water part are in contact respectively through the gas permeable membrane.