Biodegradable polymers generally decompose in the various media in our environments. These environments contain soils, seawater, and activated sludge. If biodegradable materials waste is discarded, they decompose in these media. The biodegradation process of biodegradable polymers was investigated by scanning electron microscopy. Polycaprolactone, polybutylene succinate, and P(3HB-co-3HV) were tested. The shapes of holes on the decomposing surfaces are different according to the biodegradation media. Semispherical holes are observed on the surfaces of polybutylene succinate films degraded in activated sludge and cracks are observed on the surfaces of polycaprolactone films degraded in soil.