Driving assist method and driving assist device

A driving assist device comprising:

• a controller that calculates a travel route over which a host vehicle is caused to travel and that executes a driving assist control based on the travel route, the controller including:
• a setting part that sets an illumination area based on the travel route where a direction indicator light indicating the host vehicle is to exit the roundabout is to be illuminated;
• an illumination area arrival assessment part that assesses whether or not the host vehicle has arrived at the illumination area set by the setting part while the host vehicle is traveling on the roundabout;
• and
• a direction indicator light control part that, when the host vehicle is to exit the roundabout and the host vehicle is assessed by the illumination area arrival assessment part to have arrived at the illumination area, performs a control to determine to illuminate the direction indicator light that indicates the host vehicle is to exit the roundabout,
• the setting part being configured to set the illumination area from a positional relationship between a host vehicle entrance for the host vehicle and a host vehicle exit for the host vehicle in the roundabout based on the travel route.