Abstract: A fireproof windowpane in which a glass plate having metallic wires incorporated therein is fitted in the grooves of a mounting metal frame to a depth corresponding to at least about 1.6 times the thickness of the glass plate at least at its upper edge. Also provided is a mounting metal frame for mounting fireproof windowpanes which has grooves for receiving the metallic wire-containing glass plate therein to the aforesaid depth. The fireproof windowpane can withstand fire or high temperatures over a long period of time, and is useful for preventing spreading of a fire and for aiding in fire extinguishing activities.