The apparatus for assisting driving of host vehicle includes a first sensor mounted to the host vehicle and having a field of view in rear of the host vehicle, the first sensor to obtain rear image data; a second sensor selected from a group consisting of a radar sensor and a LiDAR sensor and mounted to the host vehicle, the second sensor to have a field of sensing in rear of the host vehicle and obtain rear detecting data; and a controller to process the rear image data and the rear detecting data. The controller may be determine a possibility of a collision of a rear object located at the rear of the host vehicle based on processing the rear image data and the rear detecting data, and to adjust a seat of the host vehicle to a preset position based on an expected collision of the rear object.