Abstract
The SELENE (SELenological and Engineering Explorer) is a Japanese lunar polar orbiter with 14 scientific instruments. The XRS is to map major elemental composition in 20km spatial resolution, to provide the clue to understanding the lunar evolution. Energy resolution and efficient detection area of the XRS has been much improved by using arrays of Si CCD with 100cm2 detection area and ultra-thin beryllium window for better transparency at low energy. We present the specification, performance and current status of the XRS and method of remote X-ray spectrometry.