An object is to provide means for suppressing the formation of any isomer of luliconazole on account of any influence of, for example, the humidity and the light and improving the stability. Disclosed is a method for differential evaluating a crystal of luliconazole, comprising differential evaluating the crystal by using, as indexes, surface free energy of the crystal of luliconazole and a ratio of a polar component of the surface free energy, wherein the crystal is evaluated to be stable on condition that the surface free energy is smaller and the ratio of the polar component is lower.
