Abstract: The present invention relates to a microemulsion concentrate containing cyclosporin as an active ingredient, dimethylisosorbide as a cosurfactant, oil and a surfactant which is suitable for the formulation of a soft capsule for oral administration, said cyclosporin, dimethyl isosorbide, oil and surfactant being present in the ratio of 1:1-5:1-5:2-10, and preferably in the ratio of 1:2-4:2-5:2-4:7, by weight. Since dimethylisosorbide has substantially no membrane permeation property, the soft capsule preparation according to the present invention is outstandingly stable in comparison with the soft capsules containing ethanol, propylene glycol, transcutol, glycofurol, etc., as a cosurfactant in the prior art, and further provides an advantage in that the pharmaceutical effect, appearance and composition content of the soft capsule according to the present invention are not changed.