Provided are a crystalline resin cured product which shows high thermal conductivity, low thermal expansion, high heat resistance, low moisture absorption, and good gas barrier properties and a crystalline resin composite material produced therefrom. Further provided is a method for producing the crystalline resin cured product and the crystalline resin composite material. The crystalline resin cured product is obtained by the reaction of an aromatic diglycidyl compound or a diglycidyl resin with an aromatic dihydroxy compound or with a dihydroxy resin and it shows a heat of melting of 10 J/g or more in differential thermal analysis while the endothermic peak corresponding to the melting appears in the range of 120 to 320° C. The crystalline resin composite material is obtained by combining the crystalline resin cured product with a filler or a base material. The crystalline resin cured product has a unit represented by -A-O—CH2—CH(OH)—CH2—O—B—, wherein A and B are divalent aromatic groups.