In this study, a single droplet experiment and a spray combustion experiment for an emulsified fuel were carried out. The purpose of the single droplet experiment was to investigate the characteristics of the secondary atomization and the dominant factor in determining micro-explosion or puffing. In the spray combustion experiment, the spray combustion characteristics of the emulsified fuel used in the single droplet experiment were investigated. In the single droplet experiment, individual emulsified fuel droplets suspended from a thermocouple were set into an electric furnace. As a result, many forms of secondary atomization were observed. While the superheat temperature ranged between 50 and 80 K at the occurrence of micro-explosion, it ranged between 20 and 50 K when puffing occurred. It was found that the probability of the micro-explosion increased with an increase in the superheat temperature. The emulsified fuel had a drastic effect on the spray combustion characteristics. When the emulsified fuel was used, the gas temperature was reduced in the upstream region. However, the gas temperature increased rapidly and there was no peak of the gas temperature in the axial direction, unlike kerosene. Moreover, the radial distribution of the gas temperature of the emulsified fuel became uniform, also unlike kerosene, as a result of the improvement of the evaporation and the mixing caused by the secondary atomization as shown in the single droplet experiment.