In this review, the various models to estimate wildlife abundance are organized for promoting the correct application of them in animal ecology. If individuals of the target wildlife are distinguishable, the capture-recapture (CR) model and the spatially explicit capture-recapture (SECR) model can be applied to the closed population and the Jolly-Seber (JS) model can be applied to the open population. If not, the distance sampling, N-mixture model, random encounter (RE) model, random encounter and staying time (REST) model, and removal sampling can be applied to the closed population, and the harvest-based model can be applied to the open population. Recent advances in the hierarchical model and the integrated population model (IPM) make it possible to model the abundance and demographic rate of the wildlife by considering the ecological process of the target wildlife and observation process of them and to utilize the various but fragmented data. Then, the formalization of the abundance estimation model as a hierarchical model and the construction of the IPM by considering the available data and biological characteristics of the target species are useful for future research.