Method for manufacturing roadbed material

Provided is a method for easily producing a roadbed material from which hexavalent chromium does not readily elute, using, as a raw material, a crushed product of a hardened cementitious material containing hexavalent chromium. A method for producing a roadbed material, which comprises a carbonation step for carbonating a crushed product of a hardened cementitious material containing hexavalent chromium using a carbon dioxide-containing gas having a temperature of 50-140 DEG C and a water content of 1.5% or more, to obtain a roadbed material in which hexavalent chromium is less likely to elute than before the treatment. It is preferable that the production method comprises, prior to the carbonation treatment step, a crushing step for crushing the hardened cementitious body containing hexavalent chromium to obtain a crushed product containing 50% by mass or more of a crushed product having a particle size of 100 mm or less and 1% by mass or more of a crushed product having a particle size of 2.36 mm or less. 本