This invention provides a novel steroid derivative having the structure of an ester between the carboxyl group of a quinolonecarboxylic acid and the alcoholic hydroxyl group in 21-position of a steroid compound, which has the following formula (I) (wherein R is a hydrogen atom, a methyl group or a hydroxyl group) or a pharmacologically acceptable salt thereof. <IMG> (I) The compound of this invention has high antibacterial activity and antiinflammatory activity in one
