DRIVING ASSIST DEVICE

A driving assist device for a vehicle sets a a roadway area ahead of the vehicle, detects an avoidance target existing ahead of the vehicle, and executes collision avoidance control that avoids a collision between the vehicle and the avoidance target. The collision avoidance control is more likely to be executed when the avoidance target is within the roadway area than when the avoidance target is outside the roadway area. The driving assist device detects a roadway end object and a first lane marking of a first lane in which the vehicle exists. An imaginary position is a position apart from the detected position of the roadway end object toward the first lane by a constant distance. The driving assist device sets the imaginary position or the detected position of the the first lane marking as a boundary position of the roadway area based on a predetermined condition.