To provide a method for producing soap in a cold process in a shorter time than by a conventional method.

The production method of soap includes steps of: preparing an emulsified product 15 by mixing fat and oil 11 with an alkali 12; filling a package container 16 with the emulsified product 15 while the emulsified product 15 is in a fluid state; and saponifying the emulsified product 15 in the package container 16. A heat insulating container is preferably used as the package container 16. The emulsified product 15 is preferably prepared at 60°C or lower. After the package container 16 is filled with the emulsified product 15, the package container 16 is preferably sealed.