To enable a carbonized material production kiln to be maintained in a simple manner when an exposed surface on a side wall of the kiln is cracked, to prevent the kiln from easily cracking by heat to thereby prolong the life of the kiln itself, and to increase heat retention efficiency to thereby increase carbonization efficiency even during periods of cold temperatures such as the winter season. The carbonized material production kiln is formed by stacking cubic concrete blocks each having no reinforcing iron so that recombination of up to six faces of each cubic concrete block becomes possible, wherein a heat storage/retention member such as stones is filled in an exhaust space formed between a kiln floor iron plate and a kiln bottom so as to store heat, thereby preventing a decrease in carbonization efficiency even at cold temperatures.