A power window controlling device, which detects an obstruction-caught state without misunderstanding even if the electric potential at the power source drops abruptly, which comprises switches, an electric motor, a drive system, a drive controller, a rotation sensor, a motor speed calculating device, a source voltage detecting circuit, a data signal generating device and a motor torque calculator. The motor torque calculator calculates correcting data of motor torque on basis of a correcting data signal given from the data signal generating device and a rotational speed signal of the motor given from the motor speed calculator, and compares the correcting data of the motor torque with the predetermined criterion value in a case where the electric potential of the power source changes.