A medical instrument includes a first grasping member and a second grasping member that approach and separate from each other, a rotating body that is rotatably installed on a rotation shaft fixed to the first grasping member, an open-close link whose first end is rotatably connected to a first rotation shaft provided on the second grasping member and whose second end is rotatably connected to a second rotation shaft provided on the rotating body at a distance from the rotation shaft, and a manipulating member rotating the rotating body. When the rotating body is rotated in a predetermined direction, the first grasping member and the second grasping member approach each other while the second rotation shaft approaches an imaginary straight line connecting axes of the rotation shaft and the first rotation shaft.