An apparatus for automatically controlling a vehicle speed includes a first unit configured to drive data of a vehicle from electric control units (ECUs) to determine driver's habits, a second unit configured to receive the drive data from the ECUs and receive a driver's habit value from the first unit to control a speed of a smart cruise control apparatus, a third unit configured to guide the driver visually or audibly by using information about a result of controlling the smart cruise control apparatus by the second unit, the drive data and driver's habit information, and a fourth unit configured to monitor the result of controlling the smart cruise control apparatus or drive data generated while the smart cruise control apparatus is operated to transmit the controlling result or the generated drive data to the first unit.