A vehicular light distribution control system (100) controls a light distribution of headlights (3). The control system includes the following parts. The vehicle detecting part (10) detects an anterior vehicle driving in front of an occupants vehicle. The unirradiated region setting part (12) sets a region where the anterior vehicle detected by the vehicle detecting part (10) exists as an unirradiated region. The vehicle motion estimating part (13) estimates an ensuing motion of the anterior vehicle detected by the vehicle detecting part (10). The unirradiated region adjusting part (14) adjusts a size of the unirradiated region set by the unirradiated region setting part (12) depending on an estimated result 15 of the vehicle motion estimating part (13).