In accordance with a vehicle motion control apparatus, a steering angle (.theta.h) of a steering wheel is determined on the basis of a rotation angle (.theta.pm) of an assist motor (24m) detected by a rotation angle sensor (24s) and a rotation angle (.theta.vm) of a gear ratio variable motor (32m) detected by a rotation angle sensor (32s), and a VGRS control process (40a) of a gear ratio variable mechanism is executed on the basis of the determined steering angle (.theta.h). Accordingly, since the steering angle (.theta.h) of the steering wheel is determined on the basis of the rotation angle (.theta.vm) used for the VGRS control process (40a) of the gear ratio variable mechanism and the rotation angle (.theta.pm) used for an EPS control process (30a) of an EPS actuator, it is possible to obtain the steering angle (.theta.h) of the steering wheel without a steering angle sensor. Therefore, it is possible to reduce the number of the parts of a vehicle motion control apparatus.