PURPOSE: Provided is core drill to improve early drill-workability by reducing frictional resistance in positioning surface and increase cutting effect by facilitating discharge of cutting powder or slurry. CONSTITUTION: The core drill comprises the following as: cylindrical core body with constant diameter and length; multi-adhered segment tip which cutting thickness face is characterized by consisting of acute thickness part tilted to make frictional resistance decrease on cut materials and which cuts the materials at a constant distance on the lower part of the core body, which the acute thickness part is tilted from outside arc or inside arc of the segment tip or tilted from both sides of outside arc and inside arc.
