The object of the present invention is to provide a styrene type alkoxysilane compound which is useful as a silane coupling agent or a polymerizable monomer and which can easily be synthesized and is not expensive.A 3-(vinylphenyloxy)propylsilane compound represented by the following general formula: ##STR1## wherein R.sup.1 and R.sup.2 each represents a hydrocarbon group having 1 to 4 carbon atoms and n is an integer ranging from 0 to 2.