Core bits are attached to the foremost part of the core barrels to be used in direct drilling of the ground, and play the most important role among the equipment that are used in drilling. There are many types of bits classified and used according to the purpose of drilling or ground conditions, and the bits are also different in their material, shape, and performance. So, it is economical and highly effective in drilling works to use the proper bits after full understanding of the characteristics of each bit. Diamond core bit is used for the drilling of hard rocks, and metal bit is normally used for the ground or soft rocks. Impregnated core bit is normally used in case core is needed, while non core bit is used if core is not needed. However the drilling efficiency and economic feasibility increase if core Bit is used while core is not needed.