Bacteries are organism that have biggest population on Earth. There are two groups of bacteries, first group is bacteries that causing disease and other group of bacteries which provide benefits in foods, medicine, and industrial. To treat the bacteria it should be incubated because each species growth depend on certain temperature , so its need a certain temperature range. Temperature and environmental conditions can make the bacteria reproduce well. In this final project, a mesophyll bacteria incubator is designed using LM35 temperature censor that is controlled by microcontroller ATMega8535. In this modul there is several choices of time duration, 12, 24, and 48 hours, for incubation process and will be displayed on 2x16 character LCD. The MOC3041 and TRIAC L4004LT heater driver is used to turn the heater on. Based on the conducted measurement, it resulted 0,19% of error for the temperature measurement and 0.127% for the voltage measurement. For the time duration mesurement, 0,33% of error is obtained. Based on this error value, the designed modul is accurate enough to use as bacteria incubation for mesophyll species