To provide a motor controlling device and an electric power steering device which are capable of suppressing generation of a torque ripple in the case of occurrence of an electric conduction defective phase during a high speed driving in particular, and of making delicate handle steering easy.

A CPU 17 comprises: a current command value calculating part 23 which calculates a d-axis current command value Id* and a q-axis current command value Iq*; and a motor control signal generating part 24 which generates a motor control signal by executing current feedback control in a d/q coordinate system based on these d-axis current command value Id* and q-axis current command value Iq*. The CPU 17 is provided with an abnormality determining part 31 capable of detecting the occurrence of the abnormality in the case of occurrence of electric conduction defection in any of phases of a motor 12, and in the case where the abnormality is detected, executes generating of the motor control signal by making two phases other than the electric conduction defective phase an electric conduction phase. Then, in the case where a vehicle speed which speed detecting means 16 detects becomes not less than a prescribed value, the q-axis current command value Iq* is decreased gradually.