The present invention provides a process for producing a liquid crystal polyester-impregnated base material, comprising steps of (1) impregnating a fiber sheet with a liquid composition containing a liquid crystal polyester and an organic solvent dissolving the liquid crystal polyester, (2) removing the organic solvent from the impregnated liquid composition, thereby forming an intermediate, and (3) heat treating the intermediate at 270° C. or higher and a lower temperature than a pyrolysis temperature of the liquid crystal polyester.