摘要： 作者认为，股权转让合同原则上自合同成立之时起生效，除非法律法规明文规定批准或登记生效要件。合同生效时间不同于合同项下股权的变动时间。不得以股权变动尚未发生为由否认股权转让合同的效力。有效股权转让合同仅产生卖方将股权让渡买方的合同义务，而非导致股权的自动、当然变动。倘若某股东向非股东转让股权时未尊重老股东同意权与优先购买权，则股权转让合同为可撤销。即使履约导致股东超过50人，股权转让合同与公司亦为有效。卖方出资存在瑕疵的，买方股东资格也存在瑕疵，但此种瑕疵并不必然影响合同的效力。主张慎重对待和处理无效或可撤销的股权转让合同。

关键词: 股权转让合同 , 有限责任公司 , 股权变动 , 同意权 , 优先购买权 , 无效合同 , 可撤销合同

Abstract: The author argues that the contract of share transfer shall be valid upon the reach of the agreementsbetween the buyer and seller，unless the mandatory rules stipulate otherwise．The time for the contract to be valid is dif-ferent from the time for the shareholding to be changed．The contract may not be invalidated on the ground of the failureof the change of the shareholding，as the valid contract only obligates the seller to convey his shares to the buyer，butdoes not automatically cause the change of the shareholding．If a shareholder sells his shares to a buyer without infomfingother existing shareholders，such contract shall be avoidable．Even if a transaction produces more than fifty shareholders，both the transaction and the corporation in question are valid and lawful．Even if a seller made defective contributions tothe corporation，the transaction is not necessary invalid．The avoidable and invalid contracts of share transfer should betreated carefiAly．

Key words: Contract of share transfer；Limited liability corporations；Change of shareholding；Right to consent；Pre&mdash, emptive right to buy shares；Null and void contract；Avoidable contract