The driving support device executes self-position estimation of an own vehicle by odometry. In the case where landmarks around the own vehicle are detected, the driving support device corrects the self-position and creates an environment map. Next, the driving support device estimates the correction accuracy of the estimated self-position. In the case where the correction accuracy is high, the driving support device selects a first operating mode of driving support. In the case where the correction accuracy is low and the accuracy of odometry is also low, the driving support device selects a second operating mode of driving support. The second operating mode is a mode in which the degree of driving support is lower than that in the first operating mode.