A 2-silyloxy-4,5,6,7-tetrahydrothieno�3,2-c!pyridine represented by the formula (I): ##STR1## wherein R.sup.1, R.sup.2 and R.sup.3 each independently represent an alkyl group having 1 to 10 carbon atoms or an aryl group,and a salt thereof and a process for preparing the same, and a 5-alkyl-2-silyloxy-4,5,6,7-tetrahydrothieno�3,2-c!-pyridine represented by the formula (IV): ##STR2## wherein R.sup.1, R.sup.2 and R.sup.3 represent the same meanings as described above; R.sup.4 represents a hydrogen atom, an alkoxycarbonyl group having 2 to 10 carbon atoms, an acyl group having 2 to 10 carbon atoms or a cyclo-alkylcarbonyl group having 4 to 10 carbon atoms; andR.sup.5 represents a halogen atom, an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms,which is useful as a synthetic intermediate of an antiplatelet medicine and an elastase inhibitor, etc., and a process for preparing the same.