[PROBLEMS] To provide a more effective and simplified method of producing a liquid nutritional food such as a fluid diet or a medical diet. [MEANS FOR SOLVING PROBLEMS] The above problem has been solved by providing a method of producing a liquid nutritional food which comprises a mixing step (12) wherein starting materials are mixed together, a sterilizing step (13) wherein sterilization is conducted by heating and a homogenizing step (15) wherein homogenization is conducted, characterized in that a multifunctional mixing tank, whereby heating, cooling and agitating can be at least conducted under reduced pressure and is used as a mixing tank in the mixing step (12) and the average diameter of fat spheres is regulated to 1 m or less.
