A traffic control support system for accurately predicting, when an irregular event occurs, a traffic state and an influence of the event on the traffic state, is provided. The traffic control support system includes calculation means for calculating, based on a relation between a flow rate and a density of traffic and a predicted value of the density in a regular state in each of a plurality of locations, an estimated value of the density in each of one or more locations at a specific time after an event starting time representing a time at which an irregular event occurs in at least one of the plurality of locations, and display control means for displaying an influence of the irregular event on traffic in each of one or more locations, based on an estimated value of the density.