The appointment of guardian by a will specified within Article 1093 of the ROC Civil Code is the extension of parent's right. As such, the guardian appointed by the parent by means of a will, which shall be restricted under the exercise principle of the parents' right accordingly. This article would like to explore how it will affect the effect upon appointment of guardian by a will under the exercise principle of the parents' right. In addition, in case the appointment of guardian by will executed by the parent is void then the guardian should be determined under the statutory order specified by Article 1094 of the Civil Code. Does it sound reasonable? What is the ideal function for determination of the guardian? This would be also the key point of this article.