The present invention relates to a non-animal soft capsule shell composition having improved disintegration stability and shell hardness. More particularly, the present invention relates to a non-animal soft capsule shell composition and to a method for preparing same, in which an antioxidant and a disintegration aid are added to the non-animal soft capsule shell composition that is typically made of starch or a starch derivative, gums, a plasticizer, a buffering agent, and purified water which inhibit starch retrogradation and thus inhibit an increase in disintegration stability and capsule shell hardness, thereby improving disintegration stability and shell hardness.