PURPOSE: To improve durability and interlaminar strength by using a prepreg formed by reacting an epoxy resin, phenols and a curing agent at the time of manufacture while specifying the glass transition point temperature of a curable resin and ply separation strength between glass cloth respectively.

CONSTITUTION: A copper-clad laminate is applied as the substrate of a printed circuit board, and constituted while mainly comprising a specific prepreg. The specific prepreg is formed by reacting a polyfunctional epoxy resin, a bifunctional epoxy resin, bivalent phenols and a curing agent at the time of the manufacture of the prepreg. The glass transition point temperature of a curable resin is set at 145°C or higher. Ply separation strength between glass cloth in the laminated board is set in 0.9kgf/cm2 or more. Accordingly, the copper-clad laminate having excellent high heat resistance, interlaminar strength, shock resistance and workability while having high interlaminar strength in spite of the high glass transition point temperature and high reliability is obtained.