A method for manufacturing a structure material is a method for manufacturing a structure material that includes a thermoplastic resin, reinforced fibers, and voids. The method includes: a first process for arranging a structure precursor comprising the thermoplastic resin and the reinforced fibers in a mold with a surface temperature of 80° C. or less; a second process for raising the surface temperature of the mold up to a temperature at which a storage elastic modulus (G′) of the structure precursor is less than 1.2×108 Pa; a third process for lowering the surface temperature of the mold down to a temperature at which the storage elastic modulus (G′) of the structure precursor is 1.2×108 Pa or more; and a fourth process for removing a structure material obtained after end of the third process from the mold.