The present invention provides an organopolysilmethylene represented by the following general formula (1): wherein R1 is, independently of each other, a group selected from the group consisting of an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, an alkoxy group, a hydroxy group, R3SiCH2— and R3SiO—, wherein R is, independently of each other, a group selected from the group consisting of an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, an alkoxy group, and a hydroxy group, m is an integer of 1 to 100, and n is an integer of 1 to 100, and wherein at least two out of R1's and R's are an alkenyl group.