NOVELTY - A hydroxyl-containing fluoropolymer (A) and silicon-containing compound are reacted in the presence of a solvent and metallic compound, and a fluoropolymer (B) having hydrolysable silyl group is produced. The usage amount of metallic compound is 40-140 ppm by metal atom conversion.    USE - Manufacture of hydrolysable silyl group-containing fluoropolymer for manufacturing dehydrating agent-containing composition, and coating material composition (all claimed). Uses include but are not limited to motor vehicle components, electric train, aircraft, civil engineering components, building materials, road components, communication apparatus, electrical and electronic components, coating material for mirror of solar power generation, and solar cell back sheet.    ADVANTAGE - The fluoropolymer having excellent storage stability and pot life is manufactured.    DETAILED DESCRIPTION - A hydroxyl-containing fluoropolymer (A) and silicon-containing compound of formula: OCN(CH2)mSiX1nR13-n are reacted in the presence of a solvent and metallic compound of formula: MZn, and a fluoropolymer (B) having hydrolysable silyl group of formula: -OC(O)NH(CH2)mSiX1nR13-n is produced. The usage amount of metallic compound is 40-140 ppm by metal atom conversion.    R1=H or 1-10C monovalent hydrocarbyl;    X1=1-5C alkoxy;    n=1-3;    m=1-5;    M=metal atom having oxidation number of 2-4 and electronegativity of 1.3-2.5;    Z=oxygen, alkoxy, aryloxy or acyloxy;and    n=oxidation number of M, and exhibit number of Z bonded with M.    INDEPENDENT CLAIMS are included for the following:    (1) composition containing the fluoropolymer and a reaction solvent;    (2) manufacture of composition containing the fluoropolymer and a weak solvent, which involves producing composition containing the fluoropolymer and reaction solvent other than weak solvent, and substituting weak solvent by replacing reaction solvent;    (3) composition containing fluoropolymer and weak solvent;    (4) manufacture of dehydrating agent-containing composition, which involves adding 0.1-10 parts mass of dehydrating agent chosen from orthoacid ester, acetal and hemi-acetal with respect to 100 parts mass of fluoropolymer;    (5) dehydrating agent-containing composition; and    (6) coating material composition containing the fluoropolymer, dehydrating agent and coating material additive.