The present invention relates to an agent for killing HIV-1-infected cells, comprising a compound represented by formula (I):wherein Ar1 and Ar2 are the same or different and represent a substituted or unsubstituted aromatic group, and X represents —CH2O— or —CH═CH—, its salt, or their solvate, and a combined preparation for simultaneous, separate, or sequential administration in treating or preventing HIV-1 infection, comprising two separate preparations: (a) a preparation comprising a compound represented by the formula (I), its salt, or their solvate, and (b) a preparation comprising an anti-HIV-1 drug.
