Abstract: The principle to control and suppress the corkscrew movement of beam centroid is represented in this paper. The formulae for magnetic fields induced by the cosine (cos) coil and sine (sin) coil are given. The results of two types of the coil-arrangement design are compared with each other. It is pointed out that the cos or sin coil designed in a more exact method can turn the steering field more effectively than that in a simple method.