To provide an aliphatic polyester resin foam which is light-weighted and excellent in strength, does not contain additives remaining after decomposition of the foam to exert bad influences, has a light environmental load, and exhibits sufficient strength to be serviceable as a structure without using a long chain-branched aliphatic polyester resin.

The aliphatic polyester resin foam is biodegradable and contains neither long chain-branched and/or crosslinked components nor residues of chemical blowing agents, where the aliphatic polyester resin comprises a mixture of 50-95 wt% of a first aliphatic polyester resin having a storage viscosity coefficient J" of 0.00008-0.0003 Pa-1 at a temperature 15°C higher than the melting temperature of the first aliphatic polyester resin and a shear rate frequency of 1 rad/s and 5-50 wt% of a second aliphatic polyester resin having a glass transition temperature 5-25°C lower than the cooling crystallization temperature of the first aliphatic polyester resin.