Provided is a defect grinding system and a defect grinding method capable of suppressing the occurrence of grinding failures such as excess grinding or insufficient grinding, while automating an operation to grind a defect on the surface of a target material having a three-dimensional shape, and a steel product manufacturing method employing the same.　This defect grinding system includes: a grinding device provided with a grinding tool for grinding a defect on the surface of a target material; a shape measuring device for measuring the three-dimensional shape and the attitude of the target material; a defect detecting device for detecting the position of the defect on the target material; and a grinding tool control device for generating a path of the grinding tool for grinding the defect, on the basis of the three-dimensional shape and the attitude of the target material measured by the shape measuring device, and the position of the defect detected by the defect detecting device, and controlling the grinding device in such a way that the grinding tool moves along the path.