To obtain a water repellent which is excellent in providing waterrepellent effects and in improving flowing down of water drops and which imparts excellent water repellency and stain resistance to a surface to be treated by incorporating, into the repellent, a cohydrolysis product formed from a specific perfluoroalkylated organosilicon compd. (PA) and a specific hydrolyzable methylpolysiloxane compd. (MP) in water and t-butanol.

This water repellent contains a cohydrolysis product formed from a perfluoroalkylated organosilicon compd. (PA) represented by formula I (wherein R1 is a 1-4C monovalent hydrocarbon group; R2 is a 1-4C alkoxy or acyloxy; Q is a 2-10C divalent org. group; (a) is 0 or 1; and (p) is 1-12) and a hydrolyzable methylpolysiloxane compd. (MP) represented by formula II (wherein R3 is a 1-4C monovalent hydrocarbon group; R4 is a 1-4C alkoxy of acyloxy; A is methyl or a group represented by formula III; Z is 0 or a 2-10C divalent hydrocarbon group; (b) is 0, 1, or 2; (m) is 3-100; and (n) is 0-50 provided that 5 ≤ m + n ≤ 100 and that when (n) is 0, then at least one of A's at both the ends is a group represented by formula III) in a wt. ratio of PA to MP of (90:10)-(10:90).