A vehicular light distribution control system configured to control a light distribution of headlights, comprising: a vehicle detecting part configured to detect an anterior vehicle driving in front of an occupant's vehicle; an unirradiated region setting part configured to set a region where the anterior vehicle detected by the vehicle detecting part exists as an unirradiated region; a vehicle motion estimating part configured to estimate an ensuing motion of the anterior vehicle detected by the vehicle detecting part; an unirradiated region adjusting part configured to adjust, before the estimated ensuing motion occurs, a size of the unirradiated region set by the unirradiated region setting part depending on the ensuing motion estimated by the vehicle motion estimating part; and a light distribution controlling part configured to generate, before the estimated ensuing motion occurs, a light distribution pattern including the unirradiated region whose size has been adjusted by the unirradiated region adjusting part, wherein the unirradiated region adjusting part determines an expanding direction or a contracting direction of the unirradiated region depending on the estimated ensuing motion, and determines a width of expansion or a width of contraction of the unirradiated region depending on an inter-vehicular distance between the occupant's vehicle and the anterior vehicle or a relative velocity of the anterior vehicle to the occupant's vehicle, characterized in that the unirradiated region adjusting part determines an expansion rate or a contraction rate of the unirradiated region depending on an inter-vehicular distance between the occupant's vehicle and the anterior vehicle or a relative velocity of the anterior vehicle to the occupant's vehicle. a vehicle detecting part configured to detect an anterior vehicle driving in front of an occupant's vehicle; an unirradiated region setting part configured to set a region where the anterior vehicle detected by the vehicle detecting part exists as an unirradiated region; a vehicle motion estimating part configured to estimate an ensuing motion of the anterior vehicle detected by the vehicle detecting part; an unirradiated region adjusting part configured to adjust, before the estimated ensuing motion occurs, a size of the unirradiated region set by the unirradiated region setting part depending on the ensuing motion estimated by the vehicle motion estimating part; and a light distribution controlling part configured to generate, before the estimated ensuing motion occurs, a light distribution pattern including the unirradiated region whose size has been adjusted by the unirradiated region adjusting part, wherein the unirradiated region adjusting part determines an expanding direction or a contracting direction of the unirradiated region depending on the estimated ensuing motion, and determines a width of expansion or a width of contraction of the unirradiated region depending on an inter-vehicular distance between the occupant's vehicle and the anterior vehicle or a relative velocity of the anterior vehicle to the occupant's vehicle, characterized in that the unirradiated region adjusting part determines an expansion rate or a contraction rate of the unirradiated region depending on an inter-vehicular distance between the occupant's vehicle and the anterior vehicle or a relative velocity of the anterior vehicle to the occupant's vehicle.