A driver assistance device is configured to determine whether a type of a deceleration target is included in a category of a position-fixed object or a moving object, and determine whether the deceleration target is lost, and to continue the deceleration assistance on assumption that the lost deceleration target exists when the deceleration target is determined to be lost. The driver assistance device is configured to notify a driver of a host vehicle that the deceleration target is lost when the deceleration target is determined to be lost and the type of the deceleration target is included in the category of the moving object, and not to notify the driver that the deceleration target is lost when the deceleration target is determined to be lost and the type of the deceleration target is included in the category of the position-fixed object.