PURPOSE: A polygonal perforated block for an overflow-preventing bank is provided to increase weight for resisting overflow and coherence between blocks and reduce the velocity of fluid. CONSTITUTION: A polygonal perforated block for an overflow-preventing bank comprises a lower perforated block portion(110) and an upper perforated block portion(120). A protrusion is bent and formed on one side of the lower perforated block portion and a groove is bent and formed on the other side of the lower perforated block portion. The upper perforated block portion is coupled with the lower perforated block portion with sharing a hole which passes through the center of the polygonal perforated block.
