Bacteria are the most numerous organisms on Earth. There are two groups of bacteria, the first group is the bacteria that causes disease and the group of bacteria that provides benefits in the fields of food, medicine, and industry. Bacteria that will be treated must be incubated first because each bacterial species grows at a certain temperature range. Suitable temperature and environmental conditions can make bacteria breed well. In this final project, a bacterial incubator is designed which uses a PID-based temperature controller with a DS18B20 temperature sensor and is controlled by an ATMega328 microcontroller. In the design of the incubator device there is a temperature controller so that the temperature in the incubation chamber remains stable with a temperature of 37 oC for the incubation process and will be displayed by the LCD character 2x16 in the process of incubati on time. MOC3041 and TRIAC L4004LT heater drivers are used to turn on the heater so that the process produces the desired temperature. In this tool there is a temperature controller as a temperature stabilizer when incubation is running. And there is a LIMIT SWITCH that functions as an alarm or sensor on the door when the door is not tightly closed, so that the tool will facilitate the user in the incubation process.The results of measurements of the incubator that the temperature controller that has been designed produces a total error of all experiments carried out worth 0.17 at 37°C temperature testing, with a total average temperature of the bacterial incubator worth 37.06 ° C and an error on the TA tool of 0.35%.