To give no sense of unease to a drive during deceleration by setting an auxiliary target deceleration speed in the case of obtaining the target deceleration speed to a calculated target acceleration and deceleration speed to perform deceleration.

A controller 10 is provided with an operation lever 13 for directing the traveling control such as constant speed traveling and follow-up traveling to the preceding vehicle. A throttle device 21 is adapted to vary the engine output by varying a throttle opening through an output interface from the CPU, and at the time of controlling the distance between cars, CPU gives output to an automatic brake device 22 for operating an automatic brake to the wheels. The target deceleration speed operation is performed to calculate the target deceleration. After the target deceleration is obtained, deceleration is performed to reach the target deceleration speed from the current car speed. When deceleration is suddenly performed, a sense of unease is given to a driver. Then, this device sets an auxiliary target deceleration speed, thereby gradually controlling the deceleration to gradually reach the target deceleration speed.