PURPOSE: A solid fuel is provided to prevent the air pollution by neutralizing acid component among combustion gas into magnesium oxide and to improve combustibility by improving the calorie of solid fuel. CONSTITUTION: A solid fuel is manufactured by compressing and forming combustible waste after pulverizing the waste. The solid fuel mixes oil-magnesium oxide gel which is manufactured by enabling oil to be absorbed or coated to magnesium oxide. The manufacturing method of the oil-magnesium oxide gel comprises next steps. A gel magnesium oxide slurry is manufactured by adding oil component and dispersing agent to the magnesium oxide. The content of the oil component is 0.5~6 weight compared to the magnesium oxide. The content of the dispersing agent is 10~40 weight compared to the oil component.
