The invention relates to a one-way traffic roadblock, which comprises a blocking arm and a base, wherein the base is fixedly arranged on the pavement, the blocking arm is provided with a fixed end and a free end, the fixed end is used for fixing one end of the blocking arm onto the base through movable connection, and the free end is connected with the base through an elastic body so that the free end of the blocking arm can do ascending and descending type opening and closing movement above the base. In the normal use, the free end of the blocking arm ascends, the free end of the blocking arm is pressed down by wheels when vehicles normally run on the roadblock, and the vehicles can normal pass the roadblock. When the vehicles run in a direction not allowed by traffic regulations, the ascended free end of the blocking arm blocks the wheels, and the wheels cannot pass the roadblock. The one-way traffic roadblock can be used for preventing the vehicles from running in the direction not allowed by traffic regulations on highway or one-way streets, the cost of the one-way traffic roadblock is low, the installation is convenient, the damage is not easy to occur, in addition, the reliability is high, and the unattended operation is realized.