PROBLEM TO BE SOLVED: To provide a round hole deburring tool which removes burr caused by machining a round hole in a platelike material on front and rear sides simultaneously. SOLUTION: A round hole deburring tool is provided with cutting blades 1, 2, 3, 4 in a tip part of a metal bar 5 like a flat plate. These cutting blades have an edge angle. The edge angle is set to about 95 degrees to reduce a bite-in amount of the cutting blade into a burr part and keep the optimum cutting condition. A handle 6 having a grip part which can rotate centered on a support shaft 7 is provided in the tip part of the metal bar which opposes to a cutting blade part.