Aliphatic polyester film and gas barrier film

A gas barrier film, comprising a resin layer and a vapor-deposited layer which is applied on at least one side of the resin layer, wherein:

• the resin layer comprises, as its main component, an aliphatic polyester whose primary repeating unit is represented by a general formula —O—CHR—CO— (where R denotes H or an alkyl group having a carbon number of 1-3);
• the vapor-deposited layer is selected from the group consisting of an aluminum oxide/silicon oxide-based vapor-deposited layer, an aluminum oxide-based vapor-deposited layer and a silicon oxide-based vapor-deposited layer;
• a content of aluminum oxide in the aluminum oxide/silicon oxide-based vapor-deposited layer is about 20 wt % to about 99 wt %;
• a “b” value, which is calculated according to the following expression (1) based on a specific gravity D of the vapor-deposited layer and the aluminum oxide content A in wt % in the vapor-deposited layer, satisfies the following expression (2):
• Expression (1):
• b=D−0.01A
• Expression (2):
• 1.6≦b≦2.2
• (where D denotes the specific gravity of the vapor-deposited layer, and A denotes the aluminum oxide content in wt % in the vapor-deposited layer);
• a specific gravity of the aluminum oxide-based vapor-deposited layer is about 2.70 to about 3.30;
• and
• a specific gravity of the silicon oxide-based vapor-deposited layer is about 1.80 to about 2.20.