A blast-protected window, including a sash including a glass plate surrounded by a first frame, and being carried by a second frame being fixed to an opening of a structure, and a third frame, being fixed to the structure opening, and including a first peripheral surface shaped for closely covering the room side of the second frame, and being configured to block, thereby blast directed from the external environment onto the glass plate knocks onto the first peripheral surface of the third frame disposed close thereto and being configured to block the blast.