The Japanese government's Green Growth Strategy for carbon neutrality by 2050 presents a "roadmap" for the growth of the fuel ammonia industry. One of the future initiatives is the spread of ammonia co-firing and the increase in the co-firing rate in coal-fired thermal power plants, and the shift to ammonia single-fuel firing. Mitsubishi Heavy Industries, Ltd. (MHI) is developing technologies to enable ammonia co-firing for both circular firing and opposed firing systems of coal-fired boilers in order to respond to the efforts of various customers in Japan and overseas to use ammonia fuel toward the goal of carbon neutrality. This report presents the development of ammonia burners.