The Sound Fire Extinguisher is a device that suppresses flames by outputting loud sounds. In order for the sound fire extinguisher to be used in the fire fighting field, it must be compact and lightweight. In this paper, the electro-magnets were used instead of the permanent-magnets of speakers to maximize the output while minimizing the increase in the weight and volume size. A general dynamic speaker uses a permanent-magnet to generate power to the voice coil. The method applied in this study increased the magnetic flux acting on the voice coil by applying electro-magnet instead of permanent-magnet. An experiment was conducted to compare the output efficiency of the speaker with the permanent-magnet applied and the speaker modified with the electro-magnet. As a result of the comparative measurement through the experiment, the existing permanent-magnet applied speaker outputs 150 W at 1.5 kg, while the speaker applied by changing to electro-magnet outputs 500 W at 2 kg. In order to increase the output of the speaker, the weight is increased by 33% but the output is increased by 233% by applying electro-magnet instead of permanent-magnet. This enabled the Sound Fire Extinguisher to achieve high power, miniaturization and light weight.