A resin sheet that is unlikely to be affected by heat and allows prevention of the occurrence of a crack is provided. A glass fiber cloth-like material is dipped into an epoxy resin solution and subjected to curing, thereby obtaining an epoxy resin-based sheet including the glass fiber cloth-like material. The resin sheet has a haze value of 10% or lower, and preferably, has a light transmittance of 88% or higher, an in-plane retardation of not more than 2 nm, a retardation in a thickness direction of 40 nm, and a surface roughness of not more than 2 .mu.m.