Two biodegradable polymers, that is, poly(butylene succinate) (BN) and cellulose acetate (CA), were solvent-cast blended with chloroform. Homogeneous films were obtained from the blend by the addition of tetraisopropyl titanate (TP) as a compatibilizer. We measured the viscosity of the blend solution to investigate the function of TP during the blending process. From the measurement, we conclude that there are interactions among TP, BN, and CA. From optical observation and thermal measurements of the blend films, we found that the structure of blends is in a pseudostable state and that the addition of TP makes the structure units small. From thermogravimetric analyses, we found that the addition of TP decreases the thermal decomposition temperature of the BN/CA blends. From the measurements of mechanical properties of the blends, we found that changing the blend ratio can produce the materials with a wide range of mechanical properties. The hydrolysis of the blends was investigated. The molecular scission of BN/CA blends takes place uniformly not only from the outside but also from the inside of the films.