Polybutylene succinate (Bionolle) and cellulose triacetate (CTA) were solvent-cast blended with chloroform. Homogeneous blend films were obtained over a wide range of composition. The structure and properties of the blend films were investigated using various apparatuses. From Fourier transform infrared spectroscopy, wide-angle X-ray, and thermal measurements, it was found that the miscibility of Bionolle (BN) with CTA is excellent. In other words, in CTA-rich samples, it was found that BN molecules in the CTA matrix do not form a crystalline state, but forms an amorphous state. Therefore, the mechanical properties of the CTA-rich samples do not indicate the singularity before and after the melting point of purr BN. When CTA-rich samples were heated above the glass transition temperature of CTA, the BN molecules were eluted from the CTA matrix.