Three kinds of poly(vinylsilane)s, which include oligomers, were prepared by the polymerizations of vinylsilane [CH2=CHSiH3] using a radical initiator catalyst, an anionic catalyst, and a coordinated anionic catalyst (Ziegler-Natta catalyst). A colorless and transparent liquid polymer of molecular weight (M-n) 500-1500, whose structure was [-CH2CH(SiH3)-](x)[-CH2CH2SiH2-](y), and a similar liquid polymer of molecular weight (M-n) 500-1500, whose structure was [-CH(CH3)SiH2-], were obtained in high yields in the radical and the anionic polymerization, respectively. A white solid polymer, which was slightly soluble in solvent and had the structure [-CH2CH(SiH3)(-)], was obtained in the coordinated anionic polymerization. The reaction mechanisms were proposed on the basis of the reactivity of the silyl group of vinylsilane. The polymers are stable under air and have the reactive Si-H bonds. Silicon carbide was obtained by heating the polymers at high temperature under inert gas.