Japan is a country of a variety of serious natural hazards. It is composed of many islands and has long coastlines. The islands are mostly mountainous with volcanos. As Japan is located on the four earth’s crusts, there are numerous active faults which cause unstable natural slopes and, of course, strong earth-quakes. Japan has been repeatedly hit by earthquakes, some of which induced tsunamis. Japan often suffers heavy rains caused by weather fronts, typhoons and their combinations. Due probably to the global warming, the number of sudden downpours is increasing. Japan is affected by about 10 typhoons annually, which cause not only heavy rains but also high waves causing damage of coastlines. Application of geosynthetic technology has increased in Japan because of its high strength and durability. This report intro-duces Japanese challenges to utilize geosynthetic technologies to mitigate natural disasters. It covers reinforced embankments resisting overtopping caused by tsunami and river flood, geotubes for coastal protection especially for Japanese severe environment such as high waves, reinforced soil wall and/or geonet for rock fall protection works, and recent challenges to natural hazards.