Water is one of the most valuable items in the closed environment such as the space station. It will be used for human habitation and various experiments. However, it will be not supplied from the earth. Therefore, water reclamation is one of the most indispensable technologies in the space station.The water treatment processes used to be combinations of the membrane separation technologies of pre-filter (PF), ultra-filtration (UF) and reverse osmosis (RO) which has been developed for the salt-to-fresh distillation technology. One the other hand, more efficient hydrophobic membranes have been developed recentry. Using these new water treatment technology of hydrophobic membranes, the membrane distillation (MD), combined with the conventional water treatment process in now being investigated for water reclamation. The MD is expected to be most important process of the water reclamation system integrated into the space station in the future. These MD shall satisfy the following conditions: Higher separation ratio and higher water recovery efficiency Higher heat recovery Operability Handling Small Sizing In this paper, the results of investigation about the water reclamation system concerned with Life Science Experiment, which will be excuted in the space station Japanese Experiment Module (JEM), and the result of fundamental study about the MD are described.