The present invention provides a technique for controlling creep torque to prevent a vehicle from rolling backward on an upward slope. In particular, a gradient of a road is calculated in real time from a detection value of a sensor and vehicle acceleration. A maximum creep torque for preventing roll-back caused by gravity according to the gradient is calculated using the gradient and vehicle information. A first creep torque reference is calculated based on the maximum creep torque and the vehicle speed. A second creep torque reference is calculated based on the maximum creep torque and the vehicle acceleration. A torque command value according to an operation state of a brake is calculated based on the first creep torque reference value and the second creep torque reference value and the gradient. In response, a torque output of a driving motor is controlled according to the calculated torque command value.