TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The solvent (III) is at least one solvent selected from cyclopentyl methyl ether, diisopropyl ether and methyl tertiary butyl ether. Preferred Method: The obtained reaction solution is separated into solid and liquid after the reduction. The reduction is carried out by bringing the cyclic silane dianion salt into contact with the reducing agent in the presence of a solvent. At least one of the cyclic silane dianion salt and the reducing agent is added dropwise to a reaction system in which the reduction is carried out. EXAMPLE - Inside of a 300 ml four-necked flask equipped with a thermometer, condenser, a dropping funnel and stirrer was replaced with nitrogen gas, and 6.6 g N,N,N',N'-tetraethylethylenediamine, 10.0 g tetraphenylphosphonium chloride and 100 ml dichloromethane were then charged to it, to prepare a solution. Subsequently, while stirring the solution in the flask, 10.8 g trichlorosilane was slowly added dropwise from the dropping funnel in the condition of 25 degrees C. After the completion of dropwise addition, the reaction was carried out by stirring the mixture at room temperature for 24 hours, 20 ml hexane was then added to the obtained reaction mixture, and the mixture was left at room temperature for 3 days, to separate a precipitated white solid (I) by filtration. When this white solid (I) was analyzed by IR, it was confirmed to be a tetradecachlorocyclohexasilane dianion salt ((Ph4P+)2(Si6Cl142-)). Next, 2.80 g of the white solid (I) obtained above was charged in a 100 ml three-necked flask equipped with a dropping funnel and a stirrer, and was dried under a reduced pressure. Then, the inside of the flask was replaced with argon gas, and 30 ml of cyclopentyl methyl ether was added as a solvent. Subsequently, while stirring the suspension in the flask, 10 ml of a solution of lithium aluminum hydride in diethyl ether (concentration: 1 mol/l) was gradually added dropwise as a reducing agent from the dropping funnel in the condition of 25 degrees C, and then the reaction was carried out by stirring the mixture at 25 degrees C for 5 hours. Silane gas was not generated during this reaction. After the reaction, the reaction solution was filtered under a nitrogen gas atmosphere, to remove the produced salt. The solvent was removed by filtration from the obtained filtrate under reduced pressure, to obtain a colorless transparent liquid of cyclohexasilane at a yield of not less than 90%.