To inexpensively perform with a simple constitution the treatment for recycling of construction sludge to be used as a regenerated resource and the treatment of incinerated ash.

A method of recycling construction sludge includes: a step of sorting a sand component which discharges purified water while sorting solid portions according to a plurality of particle diameters from the construction sludge containing water; a step of mixing and stirring an incinerated ash, a modified soil composed of a specific solid portion further sorted from the solid portions sorted in the step of sorting, a cement and water in a specific proportion; a step of forming a solidified product by solidifying the mixture prepared in the step of stirring and mixing; and a step of generating an aggregate by crushing the solidified product obtained in a step of accumulating bulky masses. All major materials which have been treated conventionally as waste products can be used as valuable materials. Further, the regenerated aggregate which enables the recycle and use of the incinerated ash from city trashes and the like as a road base course material having strength can be obtained.