Nuclear energy is paid nore attention to be developed as energy in the world. In order to control speed of nuclear reaction in nuclear reactor, it is necessary to make absorber rod with material to absorb neutron, to be called control rod and safety rod which are key parts in nuclear reactor. For boron carbide with a large neutron absorption cross section has a strong ability to absorb neutron, it is widely  applicable to nuclear industry as material of  neutron absorption and shield.