PURPOSE: To provide a primer compsn. with excellent storage stability and coating property, consisting of an organic polymeric compd. with a silanol group linked to the siloxane-carbon bond and forming a firm bonding between adherend and curable silicone rubber.

CONSTITUTION: The compsn. consists of an organic macromolecular compd. having a silanol group linked to the siloxane-carbon bond. The macromolecular compd. is obtained by interaction of an organic polymeric component having a primary or secondary carbinol group[e.g. hydroxyalkyl (meth) acrylate polymer or its copolymer with other (meth)acrylic monomer]and a sliane compd.[e.g. tetrachlorosilane, tetracetoxysilane or methyltris(2-butanoneoxime)silane]or a condensate thereof, followed by hydrolysis. The organic polymeric component shows good adhesion to an adherend and the silanol group forms a firm bonding to curable silicone rubber.