Travel assistance device and computer program

A computer-readable storage medium storing a computer-executable travel assistance program that causes a computer to perform functions, comprising:

• obtaining a captured image that captures a surrounding environment of a vehicle by an imaging device having a start point of a driver's line of sight and an optical axis corresponding to a driver's line-of-sight direction;
• identifying, based on the captured image and map information of an area around the vehicle, a location where a connecting road is present in the captured image, the connecting road being a road connecting to a traveling road of the vehicle at a divergence point present around the vehicle;
• determining driver's visibility of the connecting road, based on a positional relationship between the location of the connecting road and a location of an obstacle present around the vehicle in the captured image;
• and
• outputting a result of the determination.