PURPOSE: To prevent entrance of dust and water to the interior of a pole case by closing the opening part of the pole case with a cover.

CONSTITUTION: An opening part 11a is formed in the upper end part of a pole case 11 in the shape of a cylinder with a bottom embedded in the floor 5a of a landing part. A handle 12a is attached to the upper end part of a columnar pole 12 inserted in the pole case 11 in a manner to be capable of freely drawing out. A disc-shaped cover 13 is openably attached to the upper end part of the pole case 11 to close the opening part 11a therewith. A sealant 14 is arranged between the upper end surface of the pole case 11 and the cover 13. By closing the opening part 11a of the pole case 11 with the cover 13, dust is prevented from entrance to the pole case 11. Further, by arranging the sealant 14 between the pole case 11 and the cover 13, entrance of water into the pole case 11 is more reliably prevented.