The present invention provides a production facility of hot dip galvannealed steel plate able to produce hot dip galvannealed steel plate on production conditions optimal at all times despite rapid changes in the steel type, plating deposition, and other external factors, wherein the production facility 1 of hot dip galvannealed steel plate is provided with a soaking/cooling furnace 7 for treating steel plate I running after leaving a rapid heating furnace 6 by at least one of soaking and cooling. Further, the soaking/cooling furnace 7 is configured to enable a change of the ratio in the furnace of the soaking region 15 for soaking steel plate I by soaking means 21 at a soaking temperature of 500° C. to 650° C. and the cooling region 16 for cooling the steel plate I by spray nozzles 22 by a 5° C./sec or more average cooling rate.