Provided are a novel foam which has a uniform fine-cell structure and is excellent in toughness and heat resistance, and a production method therefor. Also provided is a functional foam which includes the above-mentioned foam and has imparted thereto various functions. The foam includes spherical cells, in which: the spherical cells each have an average pore diameter of less than 20 μm; the foam has a density of 0.15 g/cm3 to 0.9 g/cm3; and the foam is crack-free in a 180° bending test. The functional foam includes the foam.