The purpose of this paper is to investigate the effectiveness of an inorganic coating to prevent embrittlement. Charpy impact tests were carried out, using specimens of S48C and SCM435 steel partially protected from tufftriding by the coating. The main results obtained are as follows : (1) The formations of nitriding layers were restrained by the inorganic coating regardless of the steel used. The impact value of the anti-tufftrided steel, which was treated for 120 minutes was the same as the impact value of tufftrided steel which was treated for 30minutes. (2) The transition temperature rise of the anti-tufftrided steel was considerably restrained in both type of steels when compared with the tufftrided steel. However this restraint can be attributed to alloy elements of the material and was more marked in the SCM435 steel containing Chromium. (3) This coating can be applied effectively to partially prevent embrittlement or decrease in impact value as an insulating agent of tufftriding.