To provide a method for loosening soil material and an apparatus therefor, which loosens the soil material for use in soil cement raw material, allowing construction soil and construction sludge to be recycled and compacted.

A method for loosening soil material and an apparatus therefor comprise the steps of scooping up a soil material 1 in a trommel basket 4, transferring the trommel basket 4 to above a soil loosening tank 6, rotating the trommel 5 while supplying fresh water 12 or soil loosening water 15 into the trommel 5 for loosening the soil material 1 in the trommel 5 with the rotation of the trommel 5 and the fresh water 12 or the soil loosening water 15, and supplying the soil material 1 as the soil loosening water 15 to the soil loosening tank 6 through a screen 5a of the trommel 5 while sieving gravel 14 of the soil material 1 with the trommel 5 to be separated in the trommel 5.