To provide an aliphatic-aromatic polyester improved in impact resistance, flexibility, resistance to heat decomposition, productivity, biodegradability and tear resistance.

The aliphatic-aromatic polyester comprises an aliphatic dicarboxylic acid unit, an aromatic dicarboxylic acid unit and an aliphatic and/or alicyclic diol unit, and it further comprises a constituent unit having three or more ester-formable functional groups. The content of the constituent unit having the three or more functional groups capable of forming esters is 0.0001-4 mole% in the aliphatic-aromatic polyester.