ROUTE SEARCHING DEVICE, CONTROL METHOD, PROGRAM, AND STORAGE MEDIUM

An enhanced map information processing unit 14 of a driving assistance device 1 acquires from a determination unit 13 information on surroundings of a vehicle which is needed to perform autonomous driving, and acquires from a server device 2 environment information on surroundings of a route on which autonomous driving is performed. On the basis of the acquired environment information, the enhanced map information processing unit 14 extracts, as an autonomous driving unsuitable location Pn, a location at which the accuracy of the acquirement of the sensor unit 12 is predicted not to satisfy a standard for acquiring the information on the surroundings of the vehicle needed to perform autonomous driving. An informing unit 18 alerts the extracted autonomous driving unsuitable location Pn to a user.