To provide a method for manufacturing a heat insulator for a baking furnace having low powder dust and a highly dimensional accuracy.

The method for manufacturing the heat insulator for the baking furnace comprises the steps of first wet-papermaking a slurry obtained by mixing and dispersing a ceramic fiber, an inorganic binder, a fiber coagulant and a fiber aggregate agent, and obtaining an aggregate. The method further comprises the steps of then pressing the aggregate to obtain a plate-like material 7, and they drying the material 7. The method also comprises the steps of impregnating the material with a liquid for forming the inorganic cured material layer or surface coating the liquid on the material to form an inorganic cured material layer 8 on at least the surface layer of the dried material 7, and forming the heat insulator 6 for the furnace.