[Subject Matter] To provide a printed wiring board in which no warping occurs even if interlayer insulation layers without core material are laminated on a core substrate.[Solution(s)] To lower the thermal expansion coefficient (CTE) to 20˜40 ppm, inorganic particles are added to core substrate 30 formed by impregnating glass-cloth core material with glass-epoxy resin. Furthermore, thickness (a) of core substrate 30 is set at 0.2 mm, thickness (b) of upper-surface-side first interlayer insulation layer (50A) at 0.1 mm, and thickness (c) of lower-surface-side second interlayer insulation layer (50B) at 0.1 mm. In setting so, using thin core substrate 30 and interlayer insulation layers (50A, 50B) without core material, it is thought that warping does not occur in the printed wiring board.