a base to be attached to a carriage of the hard disk drive and turned around a spindle of the carriage;

a load beam having:

a rigid part having a front end and a base end wherein the rigid part extends in a longitudinal direction thereof from the base end to the front end, said rigid part having sides edges opposing one another in a lateral direction of the rigid part which is orthogonal to the longitudinal direction, said rigid part having a planar upper surface extending between said side edges and in a first plane defined by said longitudinal direction and said lateral direction, and said rigid part having a thickness direction normal to the planar upper surface;

a resilient part connecting the base end of the rigid part and the base;

said rigid part having a base end portion and a front end portion connected together at a junction portion, said base end portion having a width in the lateral direction which increases with increasing distance from the junction portion toward said resilient part such that portions of said side edges along the base end portion form an incline angle in said first plane of said upper surface with respect to portions of said side edges along said front end portion so as to form inflections at said junction portion; and

a head for writing and reading data to and from a disk arranged in the hard disk drive, the head being arranged at the front end of the rigid part and receiving a load from the load beam;

a flexure attached to the load beam, supporting the head, and having read/write wires connected to the head;

rails formed by bending side edge portions of the rigid part along the side edges, each or said rails being formed so as to curve plate material of the rigid part upward such that the rail rises in said thickness direction of the rigid part and defines an upward curve in a second plane normal to said first plane of said upper surface, said rail having an upper rail edge portion extending continuous from the front end portion to the base end portion of the rigid part so as to form a longitudinally curved section of rail along said inflection at said junction portion so as to define a curve in a third plane parallel to said first plane defined by said upper surface; and

a deformable part formed in each of said longitudinally curved sections of the rails, the deformable part being configured more easily deformable in longitudinal and vertical directions of the rail than other parts of said rail outside of said longitudinally curved sections, wherein deformation of said deformable part in said vertical direction corresponds to a displacement of said plate material normal to and out of said first plane during said bending and the deformation in said the longitudinal direction of the rail corresponds to relative displacement of portions of said plate material in a direction parallel to said first plane defined by said upper surface and extending along a length of said rail substantially in said longitudinal direction.