To provide a method of recycling subgrade material using residual concrete difficult to dispose of in a complete recycling way or near to it, while suppressing apparatus coat and running cost low.

The method of producing the material for subgrade material using uncured residual concrete as raw material, includes processes of: recovering coarse aggregates as a first material R1 for subgrade material, using a bucket 10 for coarse aggregate separation, separating coarse aggregate C with uncured cement paste or cement mortar attached thereto from the residual concrete R, with particle sizes above a given size, and drying and curing as it is; molding the uncured mortar M in the residual concrete obtained by the separation treatment to obtain given particle sizes and shapes by using pallets 1 including a frame 2 partitioned into small sections by partition walls; curing the molded mortar by stacking the pallets having completed molding and aging; and recovering a molded body as a second subgrade material R2 by demolding cured molded mortar from the pallets.