It is an object of the present invention to provide a high frequency-capable printed wiring board material reduced in the dielectric loss tangent, weight, thickness and cost without compromising the workability, and provide electronic components using the same. The present invention provides a prepreg obtained by using a quartz glass cloth composed of low-density quartz glass fibers as a base material and impregnating the cloth with a thermosetting resin composition having a low dielectric loss tangent, and provides electronic components using a cured product of the prepreg as an insulating layer.