The purpose of the present invention is to provide a method that enables rapid film formation and makes it possible to produce a dense, colorless, transparent organic thin film having few impurities without complex control. An organic thin film is formed using a solution for forming an organic thin film, the solution containing an organometallic compound represented by formula (I) R1 nMXm-n (I) (in formula (I), R1 represents a C14-C30 aliphatic hydrocarbon group optionally having a substituent or linking group, or a halogenated C14-C30 aliphatic hydrocarbon group optionally having a substituent or linking group; M represents at least one metal atom selected from the group consisting of a silicon atom, a germanium atom, a tin atom, a titanium atom, and a zirconium atom; X represents a hydroxyl group or an -NR2 2 group, at least two of the X representing an -NR2 2 group; R2 represents a hydrogen atom, optionally substituted C1-C10 alkyl group, or optionally substituted phenyl group; R2 may be the same as or dif
