(wherein Y 1 and Y 2 may be the same or different and each represents a hydrogen atom, halogen or lower alkyl； and Z and A may be the same or different and each represents substituted or unsubstituted aryl, or substituted or unsubstituted heteroaryl) The present invention provides, for example, a method for stabilization of a diarylvinylene compound such as a compound represented by the above formula (I) or the like, or a pharmaceutically acceptable salt thereof in a solid formulation containing the diarylvinylene compound or the pharmaceutically acceptable salt thereof, which comprises allowing an inorganic substance and/or a colorant to exist in the solid formulation, and the like.
