The present invention is directed to provide a semiconductor surface treating agent; composition which is capable of stripping an anti-reflection coating layer, a resist layer, and a cured resist layer in the production process of a semiconductor device and the like easily and in a short time, as well as a method for treating a semiconductor surface, comprising that the composition is used. The present invention relates to a semiconductor surface treating agent; composition, comprising [I] a compound generating a fluorine ion in water, [II] a carbon radical generating agent; , [III] water, [IV] an organic solvent, and [V] at least one kind of compound selected from a group consisting of hydroxylamine and a hydroxylamine derivative represented by the general formula [1], as well as a method for treating the semiconductor surface, comprising that the composition is used: (wherein R1 represents a linear, branched or cyclic C1-6 alkyl group, or a linear or branched C1-4 substituted alkyl group having 1 to 3 hydroxyl groups; R2 represents a hydrogen atom, a linear, branched or cyclic C1-6 alkyl group, or a linear or branched C1-4 substituted alkyl group having 1 to 3 hydroxyl groups).