A biodegradable wax composition which comprises a wax as the base, contains a biodegradable polymer and a filler, and has a moisture permeability as measured at 40 DEG C and 90% RH of 3 g.mm/m<2>.24hr or lower. The content of the wax is preferably 65 to 95 wt.%. The biodegradable polymer preferably has a weight-average molecular weight of 200,000 or higher. The polymer preferably is polyisoprene or natural rubber and is contained in an amount of preferably 5 to 35 wt.%.