To provide .alpha.-substituted vinyltin useful for the search for function-developing substances such as pharmaceuticals/agrichemicals and functional materials and for the construction of a compound library.An .alpha.-substituted vinyltin compound represented by the formula (1), a tautomer or salt of the compound or a solvate thereof: R.sup.2CH.dbd.C(R.sup.3)Sn(R.sup.1).sub.3 (1) wherein R.sup.1 is a C.sub.1-10 alkyl group, a C.sub.2-14 aryl group or the like, R.sup.2 is a C.sub.2-14 aryl group, a C.sub.2-9 heterocyclyl group, a C.sub.3-10 cycloalkyl group or the like, and R.sup.3 is a carbamoyl group, a thiocarbamoyl group, an isocyanate group, an isothiocyanate group, a formylamino group, a thioformylamino group, an isonitrile group, an urea group, a carbamate group or the like.