The present invention relates to a novel retinoid derivative compound represented by the formula I: ##STR00001## wherein X, R.sup.1, R.sup.2 and R.sup.3 are as defined herein or pharmaceutically acceptalbe salts thereof. Also, the present invention relates to processes for producing the compound of the formula I and to an anti-cancer composition comprising the compound of the formula I. The compound of the formula I according to the present invention exerts high anti-cancer effects while not causing undesirable side effects.