Provided is a method with which a biodegradable polyester film containing polyhydroxyalkanoate can be stably produced by film blowing under practical processing conditions. A method for producing a biodegradable polyester film containing a biodegradable aliphatic polyester (A) and a fatty acid amide (B) by film blowing, the biodegradable aliphatic polyester (A) containing polyhydroxyalkanoate, the method including : a step (I) of dry-blending the biodegradable aliphatic polyester (A) with a masterbatch containing the fatty acid amide (B) and a base material resin; and a step (II) of subjecting the mixture obtained in the step (I) to film blowing.