A blade used in a centrifugal projector for projecting projection material at a processing target, wherein the blade has a front surface facing in the first rotation direction and being used to throw the projection material at the processing target, the front surface of the blade includes a first part and a second part located radially outward of the first part, the first part is formed in a straight line so that a radially outer side thereof pitches to a rear side of the first rotation direction, and the second part is formed in a curved shape and located further in the first rotation direction than an imaginary line extending the first part outward, and wherein a rearward pitch angle (θ1) of the first part is 30° to 50° relative to a plane, wherein the plane includes the rotation shaft of the blade; wherein the second part of the blade is formed so that an imaginary line connecting the rotation axis to a second part outside end portion matches a normal line, wherein the normal line is a line which includes the rotation axis; wherein the first part is configured to concentrate the projection material so as to raise the density of the plurality of pieces of projection material and wherein the second part is configured to accelerate the projection material such that the projection material is projected from the outside of the blades; and further wherein the blade is formed with a pair of planar side walls having front edges and rear edges and extending perpendicularly to the rotational axis through a radial length of the blade along circumferential sides of the front surface, the front edges being shaped straight throughout its radial length and projecting generally in the first rotation direction from the circumferential sides of the front surface, the rear edges being shaped straight in parallel to the front edges except radially inner end portions thereof from which locking portions project in a second direction which is opposite to the first rotation direction. wherein the blade has a front surface facing in the first rotation direction and being used to throw the projection material at the processing target, the front surface of the blade includes a first part and a second part located radially outward of the first part, the first part is formed in a straight line so that a radially outer side thereof pitches to a rear side of the first rotation direction, and the second part is formed in a curved shape and located further in the first rotation direction than an imaginary line extending the first part outward, and wherein a rearward pitch angle (θ1) of the first part is 30° to 50° relative to a plane, wherein the plane includes the rotation shaft of the blade; wherein the second part of the blade is formed so that an imaginary line connecting the rotation axis to a second part outside end portion matches a normal line, wherein the normal line is a line which includes the rotation axis; wherein the first part is configured to concentrate the projection material so as to raise the density of the plurality of pieces of projection material and wherein the second part is configured to accelerate the projection material such that the projection material is projected from the outside of the blades; and further wherein the blade is formed with a pair of planar side walls having front edges and rear edges and extending perpendicularly to the rotational axis through a radial length of the blade along circumferential sides of the front surface, the front edges being shaped straight throughout its radial length and projecting generally in the first rotation direction from the circumferential sides of the front surface, the rear edges being shaped straight in parallel to the front edges except radially inner end portions thereof from which locking portions project in a second direction which is opposite to the first rotation direction.