To provide a fireproof treatment implement and a fireproof treatment structure using the fireproof treatment implement that can form the fireproof treatment structure without forming a clearance between the fireproof treatment structure and a structure at the side of a fire limit body even if a through-hole is formed at the side of the fire limit body.

Insertion holes 16 for inserting conduit tubes D through are formed in a base 12 of the fireproof treatment implement 11, and first and second thermally expansive fireproof sheets 15, 19 are disposed in positions that surround the insertion holes 16, on the rear face to be the wall W side of the base 12. The base 12 includes a holding part 13f formed beforehand at the upper edge of the base 12. The fireproof treatment 11 includes an extended part 15a formed by extending the first thermally expansive fireproof sheet 15 into a position that goes over the holding part 13f.