The Hard X-ray Imager (HXI) is one of the instruments onboard International X-ray Observatory (IXO), to be
launched into orbit in 2020s. It covers the energy band of 10-40 keV, providing imaging-spectroscopy with a
field of view of 8 x 8 arcmin2. The HXI is attached beneath the Wide Field Imager (WFI) covering 0.1-15 keV.
Combined with the super-mirror coating on the mirror assembly, this configuration provides observation of X-ray
source in wide energy band (0.1-40.0 keV) simultaneously, which is especially important for varying sources. The
HXI sensor part consists of the semiconductor imaging spectrometer, using Si in the medium energy detector and
CdTe in the high energy detector as its material, and an active shield covering its back to reduce background in
orbit. The HXI technology is based on those of the Japanese-lead new generation X-ray observatory ASTRO-H,
and partly from those developed for Simbol-X. Therefore, the technological development is in good progress. In
the IXO mission, HXI will provide a major assets to identify the nature of the object by penetrating into thick
absorbing materials and determined the inherent spectral shape in the energy band well above the structure
around Fe-K lines and edges.