Cover film and electronic component packaging employing same

The present invention provides a cover film which exhibits peel strength that continuously remains constant within a range of prescribed values during peeling of the cover film, and which moreover has exceptional transparency, and does not readily give rise to "film rip" during high-speed peeling. This cover film comprises at least (A) a base material layer, (B) an adhesive layer, (C) an intermediate layer, and (D) a heat sealing layer containing a heat-sealable resin. The main component of the (B) adhesive layer is a polyester resin, and 50 mass% or more of the curing agent is isophorone diisocyanate. The (D) heat sealing layer includes (d-1) 50-90 mass% of an olefin resin comprising any one or more olefin-styrene block copolymers that contain 58-82 mass% of an olefin component and ethylene-vinyl acetate copolymers that contain 75-88 mass% of an olefin component, and (d-2) 10-40 mass% of a potassium ionomer having anti-static properties.