The application of the Arduino Nano Microcontroller-Based Automatic Disinfectant Tunnel as an Effort to Improve Health Protocols is one way to prevent the transmission of the covid-19 virus. The Department of Cooperatives and SMEs in Denpasar is a partner in the application of automatic tunnel disinfectant technology. The purpose of this activity is to introduce and implement appropriate measures to prevent the transmission of COVID-19 within the Denpasar MSMEs office. The method starts from making the needs and problems of partners, designing and systems, implementation and initial assistance, as well as providing socialization to all stakeholders at the Denpasar City Cooperatives and MSMEs Office. From the results of the activity, an automatic disinfectant tunnel tool based on the Arduino Nano microcontroller has been designed. From the test results by including 4 tunnel conditions, the automatic disinfectant runs properly. Through this community service program, the Denpasar Cooperatives and MSMEs Service have recognized the technology for applying Automatic Disinfectant Tunnel Based on the Arduino Nano Microcontroller as an Effort to Improve Health Protocols.