A travel assistance device comprising: surrounding environment imaging means for 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; connecting road identifying means for identifying, based on the captured image and map information (33, 34) of an area around the vehicle, a location where a connecting road (58, 59, 60) is present in the captured image, the connecting road (58, 59, 60) being a road connecting to a traveling road of the vehicle at a divergence point present around the vehicle; visibility determining means for determining driver's visibility of the connecting road, based on a positional relationship between the location of the connecting road (58, 59, 60) and a location of an obstacle (54, 55, 56) present around the vehicle in the captured image; and output means for outputting a result of the determination made by the visibility determining means, characterized by comprising determination region setting means for setting a determination region in a region including at least a part of the connecting road (58, 59, 60) in the captured image, the determination region serving as a target for determining the visibility of the connecting road, wherein the visibility determining means is configured to determine the driver's visibility of the connecting road (58, 59, 60), based on a positional relationship between the connecting road and the obstacle (54, 55, 56) in the determination region, and wherein the determination region setting means is configured to set the determination region in a region including a road portion of the connecting road (58, 59, 60) within a predetermined distance along the connecting road from an end portion connecting to the divergence point. surrounding environment imaging means for 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; connecting road identifying means for identifying, based on the captured image and map information (33, 34) of an area around the vehicle, a location where a connecting road (58, 59, 60) is present in the captured image, the connecting road (58, 59, 60) being a road connecting to a traveling road of the vehicle at a divergence point present around the vehicle; visibility determining means for determining driver's visibility of the connecting road, based on a positional relationship between the location of the connecting road (58, 59, 60) and a location of an obstacle (54, 55, 56) present around the vehicle in the captured image; and output means for outputting a result of the determination made by the visibility determining means, characterized by comprising determination region setting means for setting a determination region in a region including at least a part of the connecting road (58, 59, 60) in the captured image, the determination region serving as a target for determining the visibility of the connecting road, wherein the visibility determining means is configured to determine the driver's visibility of the connecting road (58, 59, 60), based on a positional relationship between the connecting road and the obstacle (54, 55, 56) in the determination region, and wherein the determination region setting means is configured to set the determination region in a region including a road portion of the connecting road (58, 59, 60) within a predetermined distance along the connecting road from an end portion connecting to the divergence point.