Since the device performance of microring resonator filters is determined by the propagation loss in the ring waveguide and the coupling efficiency between the busline and the ring, a precise and nondestructive measurement method for these parameters is needed to analyze the characteristics and to improve the performance of such filters. In this study, we propose and demonstrate a nondestructive measurement method for the loss and coupling efficiency in a microring resonator by analyzing the filter responses of throughput and drop ports. The accuracy of the method and applicable range of the propagation loss and coupling efficiency are discussed.