To provide a fixing mechanism for a plate brick which allows the plate brick to be easily assembled into and fixed to a metal frame without damaging an elastic material attached to the plate brick and the circumferential face thereof.

The fixing mechanism for the plate brick includes a holding member 30 for holding one end of the plate brick 20 and a pressing member 40 for pressing the plate brick 20 to the holding member 30 from the other end side. The pressing member 40 includes a pressing block 42 for forwardly/rearwardly moving in the direction of pressing the plate brick 20 to the metal frame 10 and pressing pieces 41 having base ends swingably mounted around the swinging shafts 43 of the pressing block 42 and inserted between an approaching metal frame side and the plate brick 20 to fix the plate brick 20, and further has an urging mechanism 47 for swinging the tip of the pressing piece 41 to an approaching metal frame side when the pressing block 42 is retracted.