To provide a defoaming silicone agent showing a good deforming effect and a foaming suppressing effect to foam of organic solvents.

The defoaming silicone agent contains, as a deforming effective component, a perfluoropolyether-modified polysiloxane represented by general formula (1), wherein X is a divalent group represented by formula: -CH2-, -CH2O-, -CH2OCH2- or -Y-NR-CO-, (wherein Y is a divalent group represented by formula -CH2- or a specific formula and R is a hydrogen atom, a 1C-10C alkyl group or a 1C-10C aryl group), R1, R2and R3are, independently of each other, a 1C-10C alkyl group or a 1C-10C aryl group, X' is a divalent group represented by formula: -CH2-, -OCH2-, -CH2OCH2- or -CO-NR-Y'-, (wherein Y' is a divalent group represented by formula: -CH2- or a specific formula and R is as defined above), a is, independently of each other, 0 or 1, z and z' are, independently of each other, an integer of 5 to 100.

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