Ammonia combustion gas turbines have drawn much attention for their potential to power hydrogen-carrier applications. In 2014, 21-kW of power generation was achieved with kerosene-ammonia co-combustion using a 50-kW-class micro gas turbine. In 2015, methane-ammonia co-combustion and 100% ammonia gas combustion were separately employed to generate 42-kW of power in both cases. However, this microgas turbine still requires kerosene to start. In gas turbines, the suitability of the air flow for ignition depends on the fuel. Low-NOx combustors were developed using the staged combustion concept to achieve rich-lean combustion. These combustors can burn kerosene at start-up but not at full load. We have also developed a micro gas turbine system that utilizes 100% ammonia gas in combustion during full-load operation. However, start-up with ammonia gas is difficult without hot air. The ignition of ammonia gas is so difficult that during the startup process, a more easily ignitable fuel is also used. In this study, we developed a new 50-kW-class micro gas turbine that can be started with gaseous fuel. Start-up with methane gas was achieved using a newly designed low-NOx combustor. In addition, because hydrogen can be easily obtained from ammonia decomposition, the addition of hydrogen gas to ammonia gas has garnered attention for ammonia gas turbine applications. The application of hydrogen to initiate combustion in a micro gas turbine was also investigated.