PURPOSE: To incorporate extremely high rustproof effect in an obtained burying fitting for lightweight foamed concrete by heat-treating the fitting at 400°C or higher.

CONSTITUTION: A lightweight foamed concrete burying fitting is obtained by heat-treating it at 400°C or higher. The heat treatment is conducted at 400°C or higher or desirably 500°C or higher in an electric furnace, etc. An upper limit of the treating temperature is a temperature which does not thermally deform the fitting, and in view of energy cost, it is meaningless even if it is considerably high. Its treating time is normally 5-10min. The thus obtained fitting is desirably then rustproofed by rustproof agent which contains resin, pigment as main ingredients, buried in the case of molding a lightweight foamed concrete panel, and hydrothermally cured by an autoclave.