The ALOS is a Japanese sun-synchronous earth observing satellite scheduled to be launched in 2002. ALOS carries both optical and microwave high resolution imaging sensors, i.e. the Panchromatic Remote-sensing Instrument for Stereo Mapping (PRISM), the AVNIR-2, and the PALSAR, mainly for cartographic use, environmental and hazard monitoring, the earth resources investigations. PALSAR is an advanced-type follow-on SAR of the JERS-1/SAR and developed jointly by NASDA and MITI/JAROS. PALSAR is operated at an L-band frequency with parallel and cross polarization in a variety of beam selection modes providing different spatial resolutions, i.e. 8m/10m and 20m, incidence angles, and swath widths. In addition, the ScanSAR mode enables to serve a wide region up to 350 km with a low resolution ecology, hydrology, glaciology, oceanography, etc., together with the use of radar interferometry techniques for precise measurements of surface topography and its changes caused by earthquakes, volcanic activities, etc.