To provide a base material for molding a fiber-reinforced plastic and a molding method of the fiber-reinforced plastic which make it possible to mold a fiber-reinforced plastic member of a large area having few voids and being excellent in surface design properties, in a short tact time and with excellent productivity.

The base material for molding the fiber-reinforced plastic has a constitution wherein a partially impregnated prepreg of one sheet or a plurality of laminated sheets is covered, on both of the upper and lower sides, with thermoplastic resin sheets and the lapping parts of the upper and lower thermoplastic resin sheets are joined to form a closed space surrounding the periphery of the partially impregnated prepreg, and the pressure inside the closed space is reduced to -4.052×104 (Pa) or below. The base material is used in the molding method of the fiber-reinforced plastic.