To provide a biodegradable card base which is free of bending and cracking even when carried in a pocket of trousers or the like.

In regard to the biodegradable card base having a skin layer (A) containing an aliphatic polyester-series resin and a core layer (B) containing the aliphatic polyester-series resin, which are formed in a structure of (A)/(B)/(B)/(A) or (A)/(B)/(A), the number of times of stress crack endurance of the present card base is 500 times or more, according to a measuring method of the number of times of the stress crack endurance wherein the number of times of endurance until the card base cracks is measured under the conditions of a load 250 g, a bending angle 135° and a bending rate 175 cpm in conformity to JIS P8115.