This paper proposes a method of turning for sidewinding locomotion of snake robot. Sidewinding locomotion is employed by a snake in the desert. It was shown that this locomotion can be generated by a repetitive traveling wave. However, most study of this locomotion is realized only straight forward locomotion. Sidewinding locomotion is considered as a curve along an helix of cylinder. We propose method to turn a direction of snake robot by changing a form of a snake robot from helix of cylinder to helix of cone. In addition, we consider a center of turning point to make a snale robot turning around arbitrary radius. We applied this method to the snake robot. Experimental results of a turning radius and turning speed are shown.