Polyester-polyether segmented block copolymers of poly[(butylene succinate)-co-poly(butylene terephthalate)] (PBS-PBT) and poly(tetramethylene glycol) (PTMG) (M-n = 2000) with various compositions were synthesized. PET content in the PBS was adjusted to ca. 5 mol %. Their thermal and mechanical properties were investigated. In the case of copolymer, the melting point of the PBS-PBT control was 107.8 degreesC, and the melting point of the copolymer containing 70 wt % of PTMG was 70.1 degreesC. Crystallinity of soft segment was 5 similar to 17%, and that of hard segment was 42 similar to 59%. The breaking stress of the PBS-PTMG control was 47 MPa but it decreased with increasing PTMG content. In the case of copolymer containing 70 wt % of PTMG, breaking stress was 36 MPa. Contrary to the decreasing breaking stress, breaking strain increased from 300% for PBS-PBT control to 900% for a copolymer containing 70 wt % of PTMG. The shape recovery ratios of the copolymer containing 70 wt % PTMG were almost twice of those of copolymers containing 40 wt % PTMG.