To provide a gas hydrate formation apparatus and its formation method which can stably control the apparatus system and can improve the formation efficiency.

The gas hydrate formation apparatus comprises a deviation calculation means 13 to find a deviation of the target value of a hydrate formation amount from the actual hydrate formation amount detected by a means to detect the above formation amount and a controller 74 for calculating an order to adjust a spray amount based on the above deviation calculated by the above deviation calculation means 73; a deviation calculation means 70 to find a deviation of the target value of a pressure from the actual pressure detected by a means to detect the pressure and a controller 71 for calculating an order to adjust the pressure based on the above deviation calculated by the above deviation calculation means 70; and furthermore a deviation calculation means 76 to find a deviation of the target value of a temperature from the actual temperature detected by a temperature detection means and a controller 77 for calculating an order to adjust the temperature based on the above deviation calculated by the above deviation calculation means 76.