Disclosed is a total organic carbon (TOC) measurement apparatus capable of facilitating reduction in size of the apparatus and achieving enhanced measurement accuracy. The TOC measurement apparatus includes an organics oxidation unit, a carbon-dioxide separation unit and a conductivity measurement unit, which are integrally formed by laminating a plurality of plates to define therebetween and incorporate therein an oxidizing flow passage, an aqueous-sample flow passage, a gas permeable membrane, a measurement-water flow passage and a conductivity measuring electrode. The TOC measurement apparatus is designed such that carbon oxide in an aqueous sample is transferred from the aqueous-sample flow passage to the measurement-water flow passage through the gas permeable membrane, and a conductivity of measurement water which contains the carbon oxide and flows through a flow passage facing the conductivity measuring electrode is determined and converted to a TOC content.