Polyurethane films bent during a field application (1.5 MV/m). Doping the films with salts controlled the bending direction. With ZnBr2, Zn(ClO4)(2), and Cu(ClO4)(2) as the dopants, the films bent to the anode side. Contrarily, CH3COONa-doped, NaBr-doped, and undoped films bent to the cathode side. We also measured the space charge distribution in the films to clarify the factor that determined the direction. The measurements were carried out with a pulsed electroacoustic method. For the films that bent to the anode side, a positive space charge was observed inside the cathode during the field application. However, for the films that bent to the cathode side, there was a negative space charge inside the anode. Thus, the dopants also controlled the space charge distribution, which corresponded to the bending direction. These results suggested a causality between the field-induced bend of the film and the space charge distribution. (C) 2003 Wiley Periodicals, Inc.