To vertically attach a pole even when the support of a guide rail is inclined by composing a pole attaching part of a fixing part and a pole fixing part.

A pan stop 6 forms a smooth curved face projected upward as similar as a pan 5. The upper face 7 of a fixing part displays the curved face as similar as the pan stop 6, and a prescribed gap 10 for loosening the pan 5 between the pan stop 6 and the pan 5 is formed, and a pole fixing part 2 is extended upward from the hole 8 of the center of the upper face. The hole 8 is made to have a size in the range of a degree in which the direction can be changed, and fixing screws 9, 9 are provided on the upper face. The fixing screws 9, 9 are tightened to be locked by stabilizing the direction of the pole fixing part 2. Thereby the pole fixing part is attached to the fixing part, and since the direction can be freely changed, the pole can be vertically erected by arranging the direction of the pole fixing part vertically even in the case where the support of a guide rail is inclined by snow removal working or the like.