PURPOSE: To improve the extent of operation efficiency by attaching an eaves gutter to the backside of a beam side outer wall, while installing a funnel in ends of the eaves gutter after the end of the eaves gutter is pierced through a gable side outer wall.

CONSTITUTION: An eaves gutter 1 made up doubly with an outer gutter 11 and an inner gutter 12 is installed in parallel with a beam side outer wall of a building unit, and each of the ends 11a, 12a is installed after piercing through a gable side outer wall 4. Then, a funnel 2, whose plane form is a trapezoid, is attached to these ends 11a, 12a of both these outer and inner gutters 11, 12 via a bracket 5. Next, a partition plate 22 is erected in this funnel 2, and it partitions off the funnel inside into a sump part (a) receiving rainwater draining out of the outer gutter 11 and a drain part (b) draining the rainwater out of the inner gutter 2 from drain port 23. With this constitution, conveyance to a jobsite can be done after installation of those of eaves gutter 1 and funnel 2.