The primary aim of this study is to use microseismic events to perform a stress inversion, which has often been excluded in past studies. New insights on the seismogenic structures and stress state in northeastern Taiwan can be acquired by applying 3D velocity structure relocation, raytracing techniques, and stress inversion methods to an entire database, which permits objective and reliable selection of data for analysis. This aforementioned approach allows us to avoid the influence of a subjective selection of seismic events. Confidence intervals are also used to show the uncertainty in stress orientation. Our results show that the seismogenic structure in northeastern Taiwan is subject to complex influences from the subduction of the Philippine Sea plate and the ongoing opening of the Okinawa trough. In addition, we observed that the seismic activity of northeastern Taiwan is rather complicated. By incorporating microearthquakes and the zonation that is obtained from microearthquake sources, it becomes possible to thoroughly understand the spatial distribution of seismogenic structures in this region. Furthermore, our results also provide essential details on background stresses that can be used to study stress transfer in future studies.