To provide an exterior tool for a drainage hole which is imparted with a dustproof function without deteriorating a water discharge function.

In an exterior tool 30 for a drainage hole attached to the outside of a drainage hole 13 formed at the bottom surface 11 of a box 10 which is installed outdoors, a large number of particles 36 formed of balls of 4-5 mm diameters are filled in an expanded hollow 34 having a large cross section of a hollows (13-35) for making the drainage hole 13 communicate with the outside. Further, the expanded hollow 34 is formed at the externally fitted member 33 and the externally fitted member 33 is externally fitted to an internally fitted cylinder 31 formed by directly extending the drainage hole 13.