The present disclosure relates to an apparatus and a method for assisting driving of a host vehicle, and more particularly to a technology for controlling whether to operate a vehicle collision alert device according to the circumstances surrounding the host vehicle. An apparatus for assisting driving of a host vehicle a sensor mounted to the host vehicle and having a field of view outside of the host vehicle and capturing images; and a controller communicatively connected to the sensor and configured to predict a driving route of the host vehicle based on a vehicle control command input from a driver; determine whether the host vehicle is able to travel along the predicted driving route based on surrounding space information on the host vehicle obtained from the captured images; and control a collision alert device of the host vehicle based on a result of determining whether the host vehicle is able to travel.