To provide a vehicle steering control device capable of suppressing influence of a torque generated during driving support by an EPS device on steering of a steering wheel performed by a driver. The vehicle steering control device includes an EPS controller (first controller) that controls a speed reduction mechanism and a differential mechanism controller (second controller) that controls a differential mechanism. In addition, the vehicle steering control device has a first steering assist mode of assisting driver's steering and a second steering assist mode of performing steering independently from the driver's steering. In the second steering assist mode, the second controller controls the differential mechanism so as to cancel a torque applied to a rack-and-pinion side of the differential mechanism from the speed reduction mechanism controlled by the first controller.