Provided are a control server and a control system both capable of preventing traffic accidents more effectively. The control server is configured to control multiple traffic signals installed on a road, and includes: a pressure information obtainer configured to obtain pressure information which is outputted from a pressure sensor installed at a stop position on the road corresponding to each of the multiple traffic signals, and which includes a value representing pressure received from a vehicle running on the road; an abrupt braking information obtainer configured to, based on the pressure information, obtain abrupt braking information on an abrupt braking operation performed by the vehicle running on the road; and a traffic signal controller configured to, based on the abrupt braking information, generate a control signal for controlling the multiple traffic signals.