BS4 mannanase enzyme can increase the digestibility of chicken feed containing 20% palm kernel cake. The palm kernel cake was produced by Eupenicillium javanicum molds through coconut cake solid substrate fermentation. In its application as a feed additive, the stability of activity is something that must be considered. This study was conducted to evaluate the stability of the saccharification activity of BS4 enzymes against heating around 90°C in the feed pelleting process. The treatment was used with and without pelleting the process of starter and finisher phases broiler feed with BS4 and commercial enzymes’ addition. The parameter measured was the activity of saccharification of palm kernel cake. The results showed that the pelleting process is very influential on BS4 enzymes and can reduce 65.8 to 68.4% of its saccharification activity. While on commercial enzymes, the decrease is about 6%. It can be concluded that the BS4 enzyme is very susceptible to heat in the pelleting process so that technology is needed to protect the stability of its activity.