Abstract: A detergent composition for cleaning the surface of a substrate prior to or after application of an organic or inorganic thin film thereon, comprises: (A) a compound selected from the compounds represented by the formula: R.sub.1 --O--(A.sub.1 O).sub.n --R.sub.2 (wherein R.sub.1 represents an alkyl or alkenyl group having 1 to 7 carbon atoms or a phenyl group; A.sub.1 represents an alkylene group having 2 to 4 carbon atoms; R.sub.2 represents an alkyl or alkenyl group having 1 to 6 carbon atoms or a hydrogen atom; and n is a numerical value ranging from 1 to 6); (B) a compound selected from at least one of those represented by the formulas: R.sub.3 --O--(A.sub.2 O).sub.m --H and R.sub.4 --O--(A.sub.3 O).sub.m --H (wherein R.sub.3 represents an alkylphenyl or alkenylphenyl group having 12 to 25 carbon atoms; A.sub.2 represents an alkylene group having 2 to 4 carbon atoms; R.sub.4 represents an alkyl or alkenyl group having 8 to 25 carbon atoms; A.sub.