1. The optimum temperature of amylase activity produced by Bacillus subtilis var. M-181 was 50℃, and its activity was lost by heating to 70℃, 10 minutes without addition of salts 2. Addition of sodium salts effects for heat resistance of the amylase affected differently by kinds of the salt. Among organic sodium salts monosodium glutamate, sodium acetate as sodium propionate affected on heat resistance of the amylase relatively better effects 3. Addition of 10㎎ of sodium sulfate per ㎖ of enzyme solution (D_(30)^(40˚) 125○ ㎖); showed maximum affect on the neat resistance 4. Coexistence of calcium acetate and sodium acetate, affected on the hear resistance, remarkably.