The foam sheet of the present invention is biodegradable, can be recycled, has good processability, is lightweight, exhibits excellent appearance, has practically satisfactory heat resistance and is more acceptable to the environment.There is provided a crosslinked biodegradable resin continuous foam sheet comprising biodegradable resin, and has an expansion rate of about 1.5 to about 50 and a gel fraction of about 3% or more.There is further provided a method for producing the foam sheet comprising the steps of: (1) preparing a sheet from a resin composition comprising a biodegradable resin, a thermal decomposable blowing agent, and a crosslinking promoter; (2) irradiating the resulting sheet with an ionizing radiation to crosslink the resin composition; and (3) subjecting the crosslinked sheet to heat treatment to continuously prepare a crosslinked foam sheet.Thus, the foam sheet of the present invention can be used in a wide range of practical applications such as, for example, interior materials for an automobile, thermal insulators such as a pipe covering, cushioning materials such as a tape core and the like.