Flexible organic light emitting diodes (OLEDs) have been studied actively for the potential application to OLED display and OLED lighting. One of the key materials for flexible OLED is the flexible and transparent film substrate which can substitute ITO glass in flat panel OLEDs. In this work we deposited silicon and aluminium oxide and nitride single layer thin films on different flexible substrates such as poly(polyethylene terephthalate) (PET) and poly(polyethylene naphthalate (PEN) to investigate the gas barrier properties. After selecting the polymer film substrate and thin inorganic layer material, the inorganic/organic/inorganic multiple gas barrier was formed on film substrate by using roll-to-roll sputter and their property was examined from the viewpoint of multilayer structure and gas barrier properties for application to flexible substrate of OLED devices.