In Japan, the sewage sludge quantity has been increasing gradually as the spread of sewage increases. It is indispensable to reduce the amount of sludge because it is difficult to increase the final disposal dump newly. Especially, combustion process is selected in the big city and its outskirts. Recently, the reduction of the nitrous oxide exhausted by incinerating the sewage sludge is requested for the global warming prevention. Moreover, there is a trend that tries to use the sewage sludge that is the “carbon-neutral biomass” as the energy resource. In this report, it shows the outline of sewage treatment process, typical sludge properties and a general sewage sludge combustion method, and it introduces a recent sewage sludge treatment trend.