Civil code has shortly accepted the condition of non-transferring acts in object of sale under the article 454 and has introduced the invalidity of possession as the sanction of deviation performance.However the decree is ambiguous and brevity in two respects. Firstly whether the condition of non-transferring acts in this article belongs to affirmative condition or corollary condition and secoudly, what invalidity means. This study tries to survey, at the first place, the validity of non-transferring act condition form the standpoint of ImamiehJurisprudence. This view encompasses three standpoints of the invalidity of condition and contract the invalidity of condition and the validity of contract and the validity of both condition and contract. The study, then, analyzes the view of lawyers on the afore-mentioned themes. Finally the author’s viewpoint which is based upon the automatic cancellation of invalidity is explicated.