An organic single-crystalline film useful as a functional film in various devices is produced by selecting a liquid crystal material having a good molecular alignment regularity, disposing the liquid crystal material between a pair of boundaries exerting a thickness regulating force and solidifying the liquid crystal material while imparting a molecular alignment order by phase transition from a liquid crystal phase. The liquid crystal material may preferably be a smectic liquid crystal material which provides a uniform molecular alignment inclusive of the direction of the molecular long axis in a smectic phase.