To improve durability and sharpness for the body tissue of medical knives including knives for cutting open an affected area and surgical needles for suturing wounds. Knife A has a top end 1, a cutting edge part 2 and a knife body part 3. The cutting edge part 2 has a top side cutting edge 4 which is formed on a top side 1 having two cutting edges 4e, 4f provided on both sides of a long edge of a triangular cross section, and a knife body part side cutting edge member 5 which is formed on the knife body part side having 2 cutting edges 5g, 5h arranged in succession with the cutting edges 4e, 4f at an angle facing a square cross section. A top side angle beta between two cutting edges 4e, 4f of the top side cutting edge member is more than that of cutting edge angle alpha between two cutting edges 5g, 5f of the knife body part side cutting edge member 5, and the angle difference between the top side angle beta and cutting edge angle alpha is set in the range of 20 degrees to 70 degrees. |