PURPOSE: To straighten a bend deformation in short time without generating a crack by executing a shot peening treatment at the part located at the bend deformation inner side of a work and pressing by a pressing means from the bend deformation outside.

CONSTITUTION: The rotation of a main shaft 6 is stopped when the outside of the bend deformation of an axial work 2 is made in the state of being faced right under. Thereafter, a shot is injected to the lower part from the nozzle located just above of the groove part 2a of the work 2 and collides with the part located at the bend deformation inner side of the work 2 of the groove part 2a which is subjected to peening. The bend deformation outside of the axial work 2 is faced right above, the three rams 22a, 22b, 22c arranged at specified intervals in the axial direction of the work 2 are simultaneously descended and the work 2 is pressed. The bend deformation is thus straightened.