PROBLEM TO BE SOLVED: To provide a device capable of efficiently producing various types of composite emulsions such as a W/O/W, O/W/O and E/O/W.
SOLUTION: A dispersion phase is fed into a first space 11 through a feed opening 64, in such a state that a continuous phase has been fed into a second space 12 through a feed opening 65. At the same time, a continuous phase is fed into a third space 13 through a feed opening 66. In the above situation, by increasing the pressure of the dispersion phase fed into the first space 11, an emulsion is produced in such away that the dispersion phase is dispersed into the continuous phase in the second phase 12 via a first micro-channel 21. By increasing in pressure of the inside of the second space 12, the emulsion formed in the second space 12 is dispersed into the continuous phase of the third space 13 through a second micro-channel 22 to produce a composite emulsion as an object.