The effects of strain rate, water absorption and specimen's temperature on impact properties of a plant-derived engineering plastic, polyarnide 11, were examined. Stress-strain curves of the polyamide 11 were measured over a wide range of strain rates from 10^<-4> s^<-1> to 10^3 s^<-1>, using a quasi-static compression testing machine and a split Hopkinson pressure bar (SHPB) method. The strain rate slightly affected Young's modulus and considerably increased flow stress. In addition, the effect of water absorption and specimen's temperature from 5℃ to 65℃ on flow stress was also examined. Flow stress decreased with water absorption and increasing specimen's temperature.