保險契約為誠信善意契約，當事人互負有信賴義務。一方不得為了己身之利益，做出損害他方之行為，並需於他方履行契約過程中，提供必要之協助或為特定行為。被保險人於危險事故後之通知義務，即為履行誠信善意原則方法之一。藉由被保險人之通知，保險人得以適時處理相關程序，以利保險責任之履行並可防止被保險人與第三人共謀詐欺保險金。在傳統英美法上，及時通知為保險人給付保險金之停止條件，被保險人未履行之，保險人即毋庸負保險責任。然而，此等效果過度嚴苛，不符合現代保險法趨勢。於美國法上，多數州認為除了被保險人有遲延通知外，尚需保險人因此受到損害，始得主張免除保險責任。本文介紹美國法例對於通知義務內涵之發展，並分析兩岸法規與保險實務現況，最後提出立法及保險實務可採取行為之建議，以作為立法者及保險業者之參考。

Insurance contract is contract of good faith and the contractual parties has the duty of fiduciary to each other, which means the implied covenant of good faith imposes a burden on both parties that neither will do anything to injure the right of the other to receive the benefits of the agreement and each has to provide the cooperation and other necessary behaviors to the other when the later is in the course of implementing the contract. The insured's duty of notice in post loss is one of the ways to achieve the principle of good faith. Upon receiving the notice of loss from the insured, the insurer can handle the related issues in claim procedure in order to fulfill the contractual obligations and prevent from the insurance fraud between the insured and third party. Under the traditional opinion of common law system, timely notice is a condition precedent to coverage and delay in giving the required notice will necessarily result in a loss of coverage. However, the harsh result is against the modern trend in insurance law. The majority opinion among the states in the United States is that in addition to late notice, in order to deny coverage, the insurer has necessarily been prejudiced by it. This paper introduces the development of the contents of duty of notice in the United States, analyzes the related insurance regulations and market practice both in Taiwan and Mainland China, and refers to the regulations and precedents in the United State, so as to contribute solutions towards the amendments of insurance law and recommendations of market practice.