PURPOSE: To prevent the entering of rain water into a duct provided on the periphery of a hole section from the hole section by providing a first projecting section formed to a bank-like shape protruding from the upper surface of the duct and the second projecting section protruding from the lower surface of a lid to the opposite side of the hole section of the first projecting section to the first projecting section.

CONSTITUTION: The first projecting section 12 is formed on the periphery of a hole section 2 in the ceiling section of a duct 11 so that the entering of rain water falling on the upper surface of the duct 11 into the duct 11 can be prevented. In addition, the second projecting section 13 which is faced to the section 12 from the opposite side of the hole section 2 of the section 12 is formed from the lower surface of a lid 14 to the section 12. The rain water coming down to the lower end of the section 13 is made to fall on the side of the duct 11 opposite to the hole section 2 of the first projecting section 12 and the entering of the rain water into the duct 11 is prevented.