PURPOSE: To form a gel film by bringing a waterdrop into contact with an amin acid type oil gelling agent solution consisting of an amino acid type oil gelling agent represented by a specific general formula, a lower alcohol and an org. solvent to precipitate the amino acid type oil gelling agent.

CONSTITUTION: A droplet of an aqueous solution or a waterdrop is brought into contact with an amino acid type oil gelling agent solution constituted of an amino acid type oil gelling agent represented by formula I (wherein COR1 is a 8-18C acyl group, R2 and R3 may be same simultaneously or different and are a 4-8C alkyl group and n is 1 or 2), a lower alcohol and an org. solvent. Whereupon, the hydrophilic lower alcohol solvated with the amino acid type oil gelling agent generates phase separation to transfer to the droplet of the aqueous solution or the waterdrop and, therefore, the amino acid type oil gelling agent is precipitated and, at the same time, the gelling agent allows the org. solvent present in the periphery thereof to gel and a gel film is formed to the periphery of the droplet of the aqueous solution or that of the waterdrop to generate a capsule having water or lower alcohol enclosed in the core part thereof. This capsule contains no org. matter and includes a high purity aqueous solution.