Abstract: A polyelectrolyte solution as a disperse phase is fed into one of the chambers which are partitioned by a plate having a plurality of narrow holes (microchannels), a continuous phase is fed into the other chamber, and pressure is applied to the disperse phase forcing it through the holes into the continuous phase so as to prepare an emulsion. This emulsion is demulsified, and at the same time the disperse phase is brought into contact with a polyelectrolyte solution having a reverse electric charge to the disperse phase or a polyvalent ion solution, and a gel layer is formed around the spherical disperse phase by a polyelectrolyte reaction. Thereby, a double-structured capsule is obtained, in which the outside is insoluble gel and the inside is a polyelectrolyte solution to which a cell has been added.