An imidazole derivative represented by general formula (I) or a salt thereof, having the effect of specifically inhibiting the growth of HIV as a pathogenic virus and being reduced in toxicity. In said formula R.sup.1 represents hydrogen, C.sub.1 -C.sub.20 alkyl, C.sub.2 -C.sub.7 alkenyl, C.sub.4 -C.sub.12 cycloalkylalkyl, etc.; R.sup.2 represents C.sub.1 -C.sub.6 alkyl, C.sub.1 -C.sub.6 acyl, hydroxyiminomethyl, hydrazonomethyl or --(CH.sub.2)n--R.sup.4 (R.sup.4 being halogeno, alkoxy, hydroxy, etc.; and n being an integer of 1 to 3); R.sup.3 represents substituted or unsubstituted C.sub.1 -C.sub.6 alkyl; X and Y represent each independently hydrogen, C.sub.1 -C.sub.3 alkyl, halogeno, or nitro; and Z represents S, SO, SO.sub.2 or CH.sub.2. ##STR1##