DRIVING SUPPORT DEVICE AND DRIVING SUPPORT METHOD

A driving support device which more appropriately manages the necessity of a driving support related to collision avoidance and which effectively restrains unnecessary activation of the driving support is disclosed. The driving support device performs a collision avoidance support on a vehicle () relative to a leading vehicle () present in a travelling direction of the vehicle (), based on a time-to-collision Ta as a time that the vehicle () takes to collide with the leading vehicle (). A lateral change amount calculation portion () detects a relative lateral velocity Vy, which is a relative time-dependent change amount between the vehicle () and the leading vehicle (). A storage portion () stores therein a steering time T, which is a time required for the vehicle () to avoid the leading vehicle () by steering. The storage portion () stores therein an activation threshold TH, which is a threshold to determine activation of the driving support based on the relative lateral velocity Vy. When a relative lateral velocity Vy at a time when the time-to-collision Ta is the steering time T or more is the activation threshold TH or more, a support management portion () restrains the activation of the driving support.