The present invention provides a vehicle traveling control apparatus for a vehicle with an HST and a mechanical transmission, which are connected in tandem to each other and interposed in a traveling power transmission path between a driving power source and driving wheels. The vehicle traveling control apparatus includes a speed-change control mechanism which in turn includes a signal detection part and a control part for controlling the changing of the output speed of the HST and the shifting operation of the mechanical transmission. The signal detection part includes a load-torque detection means. The control part is designed to control the mechanical transmission and the HST based upon the detected results by the load torque detection means so that where the vehicle lies in a high load torque state, the control part downshifts the mechanical transmission to a lower speed stage, while increasing the output speed of the HST.