A steering assistance apparatus and method for a vehicle controls a steering of the vehicle by cognizing a surrounding space at the time of entry and exit of the vehicle, in a parking lot in which an entry and exit road is designed in a helix form. The apparatus includes a sensor module configured to sense at least one of an entry of the vehicle into a parking lot, and an exit of the vehicle from the parking lot, and sense whether the driving road in which the vehicle is driving is a ramp. The apparatus includes a control module configured to control steering of the vehicle within the parking lot by enabling a ramp parking area steering assist mode based on the sensing.