The existing many fuzzy traffic controllers could not be applied to the traffic congestion situation because they have been developed and applied for a non-congestion traffic flow. In this paper, therefore, we propose a traffic light controlling FLC that is able to cope with traffic congestion appropriately. In order to consider such situation as missing the green signal because of spillback of upper crossroad, it uses as an input variable a degree of traffic congestion of upper roads, which vehicles on a crossroad are to proceed to. It uses the first-order Sugeno fuzzy model for modeling nonlinear traffic flow. In experiment, we compared and analyzed the fixed traffic signal controller and the proposed FLC. As a result of experiment, the proposed FLC showed more enhanced performance than the fixed traffic signal controller.