A driving-assistance device is disclosed. The driving-assistance device in which, when a three-dimensional object is present on a course of a host vehicle, driving assistance for avoiding a collision between the host vehicle and the three-dimensional object is implemented on a condition that an unavoidable three-dimensional object is present in a predetermined range including the course, the driving-assistance device comprises a setting unit configured to set the predetermined range in the vicinity of the host vehicle at a degree of width depending on the three-dimensional object, wherein, when a plurality of the three-dimensional objects are detected within the predetermined range, the setting unit makes the degree of width smaller than when a single three-dimensional object is detected within the predetermined range.