To obtain the subject composition being biodegradable, and having extremely improved mechanical properties, especially impact resistance by including a biodegradable resin composition comprising a lactone resin and an aliphatic polyester resin, and a specific amount of a thermoplastic resin.

This biodegradable composition comprises (A) 100 pts.wt. biodegradable resin composition comprising (i) a lactone resin (e.g. a polycaprolactone having 10,000-200,000 number average molecular weight) and (ii) an aliphatic polyester resin (e.g. a polyester-carbonate resin), and (B) 5-20 pts.wt. thermoplastic resin (e.g. a rubber-modified styrenic resin having ≥10 kgf.cm/cm2 DuPont impact strength). Preferably, 5-70 pts.wt. component (i) and 95-30 pts.wt. component (ii) are preferably included in 100 pts.wt. component A. Preferably, 0.2-5 pts.wt. aliphatic amide, 0.1-3 pts.wt. liquid lubricant, 0.1-3 pts.wt. fine powder silica and 10-40 pts.wt. talc are included in 100 pts.wt. component A.