A rotor attachment structure to a shaft in a centrifuge, wherein a tip side of the shaft is a rotor coupling portion in a shape of a cylinder, a ring-shaped depression is formed in an inner periphery of the rotor coupling portion and a ring-shaped projection is formed on a side closer to a tip than the ring-shaped depression, a corner of the ring-shaped projection on an inner periphery thereof on a side where the ring-shaped depression is located is chamfered and a first shaft inclined surface is formed, and a face from the first shaft inclined surface to a bottom face of the ring-shaped depression is a second shaft inclined surface which forms an acute angle with the bottom face, and the rotor has a rotor hole into which the shaft is inserted and an attachment fitting is disposed in the rotor hole; wherein the attachment fitting comprises: a main body that is housed in the rotor coupling portion; first and second pieces (70,80) that are disposed in a piece placement hole formed in the main body so as to pass therethrough in a direction orthogonal to a rotation central axis of the rotor; characterized by a leaf spring that includes a base, two long and short extension portions (92,93) formed by being bent from both ends of the base in a same direction, and two arm portions (94,95) formed so as to extend from tips of the extension portions (92,93) in a shape of a circular arc so as to surround the rotation central axis, the leaf spring with the extension portions (92,93) and the arm portions (94,95) which are inserted into the piece placement hole via an opening formed in the main body above the piece placement hole so as to communicate with the piece placement hole; and a retainer that is mounted on the main body and puts the base between the retainer and the main body; wherein the first piece has a first groove into which the arm portion formed in the long extension portion is inserted and includes, with the first groove placed therebetween, a first side wall portion located on one end side of the piece placement hole and a first central part located on the rotation central axis, the second piece has a second groove into which the arm portion formed in the short extension portion is inserted and includes, with the second groove placed therebetween, a second side wall portion located on another end side of the piece placement hole and a second central part located on the first central part, each of outer side faces (72a,82a) of the first side wall portion and the second side wall portion has a shape of a circular arc, and, in each of the outer side faces (72a,82a), a first inclined surface (72c,82c) and a second inclined surface (72b,82b) corresponding to a shape formed by the first shaft inclined surface and the second shaft inclined surface are formed respectively, in a state in which the rotor is stopped, the first and second pieces (70,80) are positioned by the arm portions (94,95) and located in the piece placement hole, when the rotor is rotated by rotation of the shaft, the first and second pieces (70,80) move by centrifugal force so as to protrude from one end and another end of the piece placement hole, respectively, against a spring force of the leaf spring and the first inclined surfaces (72c,82c) make contact with the first shaft inclined surface, and rise of the rotor from the shaft is prevented as a result of the second inclined surfaces (72b,82b) making contact with the second shaft inclined surface. a main body that is housed in the rotor coupling portion; first and second pieces (70,80) that are disposed in a piece placement hole formed in the main body so as to pass therethrough in a direction orthogonal to a rotation central axis of the rotor; characterized by a leaf spring that includes a base, two long and short extension portions (92,93) formed by being bent from both ends of the base in a same direction, and two arm portions (94,95) formed so as to extend from tips of the extension portions (92,93) in a shape of a circular arc so as to surround the rotation central axis, the leaf spring with the extension portions (92,93) and the arm portions (94,95) which are inserted into the piece placement hole via an opening formed in the main body above the piece placement hole so as to communicate with the piece placement hole; and a retainer that is mounted on the main body and puts the base between the retainer and the main body;