A water/oil repellent composition comprising a copolymer having from 40 to 60 mass% of polymerized units derived from the following monomer (a), from 25 to 59.9 mass% of polymerized units derived from the following monomer (b), and from 0.1 to 15 mass% of polymerized units derived from the following monomer (c): monomer (a): a compound of the following formula: (Z-Y) n X wherein Z is a C 1-6 perfluoroalkyl group or a group of the following formula, Y is a bivalent organic group or a single bond, n is 1 or 2, and X is one of groups of the following formulae to when n is 1, or one of groups of the following formulae to when n is 2; C i F 2i+1 O(CFX 1 CF 2 O) j CFX 2 - wherein i is an integer of from 1 to 6, j is an integer of from 0 to 10, and each of X 1 and X 2 which are independent of each other, is a fluorine atom or a trifluoromethyl group; -CR=CH 2 -COOCR=CH 2 -OCOCR=CH 2 -OCH 2 -φ-CR=CH 2 -OCH=CH 2 wherein R is a hydrogen atom, a methyl group or a halogen atom, and φ represents a phenylene group; -CH[-(CH 2) m CR=CH 2]- -CH[-(CH 2) m COOCR=CH 2]- -CH[-(CH 2) m OCOCR=CH 2]- -OCOCH=CHCOO- wherein R is a hydrogen atom, a methyl group or a halogen atom, and m is an integer of from 0 to 4; monomer (b): a (meth)acrylate having no polyfluoroalkyl group and having a C 12-18 alkyl group; and monomer (c): the following monomer and the following monomer: monomer: a 3,5-dimethylpyrazole adduct of 2-isocyanatoethyl (meth)-acrylate, or 3-(2-butanone oxime)isocyanatomethyl-3,5,5-trimethylcyclohexyl(2-hydroxyethylmethacrylate)cyanate; monomer: a monomer having no polyfluoroalkyl group and having at least two polymerizable unsaturated groups (excluding monomer) selected from the group consisting of allyl (meth)acrylate, ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polyoxyethylene glycol di(meth)acrylate, polyoxypropylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ditrimetylolpropane tetra-(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tri(meth)allyl isocyanurate, triallyl cyanurate, and phenylglycidylethylacrylate tolylenediisocyanate. monomer (a): a compound of the following formula: (Z-Y) n X wherein Z is a C 1-6 perfluoroalkyl group or a group of the following formula, Y is a bivalent organic group or a single bond, n is 1 or 2, and X is one of groups of the following formulae to when n is 1, or one of groups of the following formulae to when n is 2; C i F 2i+1 O(CFX 1 CF 2 O) j CFX 2 - wherein i is an integer of from 1 to 6, j is an integer of from 0 to 10, and each of X 1 and X 2 which are independent of each other, is a fluorine atom or a trifluoromethyl group; -CR=CH 2 -COOCR=CH 2 -OCOCR=CH 2 -OCH 2 -φ-CR=CH 2 -OCH=CH 2 wherein R is a hydrogen atom, a methyl group or a halogen atom, and φ represents a phenylene group; -CH[-(CH 2) m CR=CH 2]- -CH[-(CH 2) m COOCR=CH 2]- -CH[-(CH 2) m OCOCR=CH 2]- -OCOCH=CHCOO- wherein R is a hydrogen atom, a methyl group or a halogen atom, and m is an integer of from 0 to 4; monomer (b): a (meth)acrylate having no polyfluoroalkyl group and having a C 12-18 alkyl group; and monomer (c): the following monomer and the following monomer: monomer: a 3,5-dimethylpyrazole adduct of 2-isocyanatoethyl (meth)-acrylate, or 3-(2-butanone oxime)isocyanatomethyl-3,5,5-trimethylcyclohexyl(2-hydroxyethylmethacrylate)cyanate; monomer: a monomer having no polyfluoroalkyl group and having at least two polymerizable unsaturated groups (excluding monomer) selected from the group consisting of allyl (meth)acrylate, ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polyoxyethylene glycol di(meth)acrylate, polyoxypropylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ditrimetylolpropane tetra-(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tri(meth)allyl isocyanurate, triallyl cyanurate, and phenylglycidylethylacrylate tolylenediisocyanate. monomer: a 3,5-dimethylpyrazole adduct of 2-isocyanatoethyl (meth)-acrylate, or 3-(2-butanone oxime)isocyanatomethyl-3,5,5-trimethylcyclohexyl(2-hydroxyethylmethacrylate)cyanate; monomer: a monomer having no polyfluoroalkyl group and having at least two polymerizable unsaturated groups (excluding monomer) selected from the group consisting of allyl (meth)acrylate, ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polyoxyethylene glycol di(meth)acrylate, polyoxypropylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ditrimetylolpropane tetra-(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tri(meth)allyl isocyanurate, triallyl cyanurate, and phenylglycidylethylacrylate tolylenediisocyanate.