A reverse flow power control device for preventing occurrence of reverse flow power from a plant having a renewable energy power generating device, a power conditioner capable of adjusting output power of the renewable energy power generating device, and a load device, and connected to an external power system, to the power system, the reverse flow power control device comprising: an input unit configured to accept actual values of the output power, load power supplied to the load device, and reception power received by the plant from the power system, and information including a minimum reception power value being a minimum value of the reception power; a storage unit configured to store the information accepted by the input unit; a calculator configured to perform a calculation of command values of the output power and the load power based on the information and the respective actual values stored in the storage unit; and an output unit configured to output the command values to the load device and the power conditioner, wherein the calculator includes: an output controller configured to calculate an output command calculation value; a load controller configured to calculate a load command calculation value; a command value re-calculator configured to calculate of by using the respective actual values, the output command calculation value, the load command calculation value, and the minimum reception power value, an output command value with respect to the power conditioner, in order to prevent a reception power value being a value of the reception power from becoming less than the minimum reception power value; and a calculation interval adjustment part configured to set of a calculation interval of generating a plurality of calculation steps, regarding a dead time in the renewable energy power generating device, the power conditioner, and the load device; wherein the command value re-calculator is further configured to calculate a change in the reception power value in an interval up to an end of the plurality of calculation steps in which a command value is reflected by the dead time, and calculates the output command value that prevents the reception power value from becoming less than the minimum reception power value. an input unit configured to accept actual values of the output power, load power supplied to the load device, and reception power received by the plant from the power system, and information including a minimum reception power value being a minimum value of the reception power; a storage unit configured to store the information accepted by the input unit; a calculator configured to perform a calculation of command values of the output power and the load power based on the information and the respective actual values stored in the storage unit; and an output unit configured to output the command values to the load device and the power conditioner, wherein the calculator includes: an output controller configured to calculate an output command calculation value; a load controller configured to calculate a load command calculation value; a command value re-calculator configured to calculate of by using the respective actual values, the output command calculation value, the load command calculation value, and the minimum reception power value, an output command value with respect to the power conditioner, in order to prevent a reception power value being a value of the reception power from becoming less than the minimum reception power value; and a calculation interval adjustment part configured to set of a calculation interval of generating a plurality of calculation steps, regarding a dead time in the renewable energy power generating device, the power conditioner, and the load device; wherein the command value re-calculator is further configured to calculate a change in the reception power value in an interval up to an end of the plurality of calculation steps in which a command value is reflected by the dead time, and calculates the output command value that prevents the reception power value from becoming less than the minimum reception power value. an output controller configured to calculate an output command calculation value; a load controller configured to calculate a load command calculation value; a command value re-calculator configured to calculate of by using the respective actual values, the output command calculation value, the load command calculation value, and the minimum reception power value, an output command value with respect to the power conditioner, in order to prevent a reception power value being a value of the reception power from becoming less than the minimum reception power value; and a calculation interval adjustment part configured to set of a calculation interval of generating a plurality of calculation steps, regarding a dead time in the renewable energy power generating device, the power conditioner, and the load device; wherein the command value re-calculator is further configured to calculate a change in the reception power value in an interval up to an end of the plurality of calculation steps in which a command value is reflected by the dead time, and calculates the output command value that prevents the reception power value from becoming less than the minimum reception power value.