A thermogravimetry (TGA) - mass spectrometry (MS) has been developed by collaborating research by KBSI (Korea Basic Science Institute) and ASTA (Applied Surface Technology Ascend) Inc. Evolved Gas Analysis (EGA) is a technique in which the gas or vapor evolved by a substance is measured using the controlled-temperature program. Normally TGA can be used to distinguish different carbon components in mixtures. When the TGA combustion signal is interfered by other oxidation reactions, TGA-MS can be used to separate the overlapping effects by monitoring CO2 evolution. In this presentation, we will introduce TOF-RGA made by ASTA Inc. and design results of interface system between TGA and MS.