Driving assistance device and computer program

Provided is a driving assistance device/program enabling selection of an appropriate parking space for parking a vehicle. A lane network which is a network representing movement into lanes that can be selected by a vehicle, a parking network which is a network representing a course that can be selected by the vehicle in a parking lot, an after-getting-out-of-vehicle network which is a network representing a course that can be selected by a user with moving means used after getting out of the vehicle are obtained, a moving cost required for movement to a destination, including movement by the vehicle to a parking space in the parking lot and movement from the parking space to the destination by the moving means used after getting out of the vehicle, is calculated using the networks, and a parking space in which the vehicle is parked is selected using the calculated moving cost.