PURPOSE: To stably and inexpensively obtain the subject composition capable of providing a coating film having good appearance and durability and having good storage stability by carrying out emulsion polymerization of a specific oligomer and a grafting agent in the presence of an acidic emulsifying agent, neutralizing the resultant polymer.

CONSTITUTION: This composition is obtained by carrying out emulsion polymerization of a cyclic dimethylsiloxane oligomer in an amount of 50-99mol% based on an amount of Si atom and a grafting agent consisting of a polyfunctional alkoxysilane containing a functional group capable of carrying out vinyl polymerization and used in an amount of 1-50mol% based on an amount of Si atom in the presence of an acidic emulsifying agent, neutralizing the resultant silicone polymer emulsion and further subjecting the silicon raw material to graft polymerization with a monomer containing a hydroxyalkyl group and polymerizable with vinyl group and used in an amount of ≤3wt.% based on total amount of the monomer and other vinyl monomer in an amount of ≤97wt.% based on total amount of the monomer in the presence of a radical polymerization initiator. In the composition, total amount of the grafting unit to total amount of a block whose recurring unit is dimethylsiloxane and the grafting unit is 1-50wt.% based on Si, and 3wt.% of the block whose recurring unit is a monomer polymerizable with vinyl is composed of a hydroalkyl functional group side chain.