Infant means new born baby and Warmer means a device for warming something . So Infant Warmer language means a device to warming the new born baby. This stuff is used as a refuge for premature infants. This research aims to design and create Infant Warmer Simulator equipped with microcontroller ATMega 32 based phototheraphy with seven segment display display. The use of infant warmer using glass heater and 2 light blue light for irradiation, in making the tool use temperature sensor LM 35 to detect temperature controlled by ATMega32 microcontroller to keep at temperature setting that is 32oC, 34oC, and 36oC. All these systems are controlled by ATMega32 microcontroller. From the research, the result of error at temperature 32oC is 0,34%, at temperature 34oC got result of error equal to 0,08%, at temperature 36oC got error result 0,41%. The result also obtained from test of blue light time that is at 1 hour test result got error result 0,05%, at 2 hour error 0,3%, at 3 hour error equal to 0,016%, at 4 hours error 0.023%. After general research, it can be concluded that infant warmer simulator equipped with microcontroller based ATMega32 based phototherapy can be used well and still in tolerance threshold value.