Masonry is one of the oldest materials used in construction. During thousands of years, prominent features of masonry such as abundance, compatibility with most climate conditions, no need for expert labor in the building process, and durability and stability, have made it a favorable choice for construction. Although a major part of the existing buildings in Iran and other places around the world are of masonry, engineers’ knowledge and apprehension of these kinds of structures are not sufficient and effective. Therefore, further research towards a more extensive understanding of masonry behavior is still indispensable. The widespread and irreparable damages inflicted on inhabitants of masonry structures, during the recent earthquakes in Iran, evidently prove this fact. In the analysis of structures, above all, a constitutive model capable of simulating the behavior of materials is needed. It is crystal-clear that due to natural variables involved, providing a precise constitutive model is impossible. The complexity of the mechanical behavior of masonry and lack of an adequate set of material data has made analysis of masonry structures much more difficult in comparison to steel and concrete structures. Providing a cyclic constitutive model presents an even greater challenge compared to a monotonic one. This study is concerned with the extending of an existing monotonic constitutive model into a cyclic constitutive one. The existing monotonic constitutive model, based on the plasticity concept, is able to simulate the hardening and softening behavior of masonry. It utilizes two different yield surfaces: a Rankine type criterion and a Hill type criterion in order to predict different failure mechanisms in tension and compression respectively. According to this constitutive model, masonry is considered as an anisotropic homogenous material which shows different behaviors along each of the material’s axes (parallel and normal to bed joints). To extend the existing monotonic constitutive model into the cyclic one, the concept of equivalent strain is used in order to utilize the uniaxial stress-strain relations in the determination of unloading and reloading paths. Unloading and reloading curves are considered to be linear in tension. In compression, unloading and reloading curves are considered to be nonlinear and linear respectively. Furthermore, the hypothesis of linear elastic unloading and reloading is assumed for the shear component. The developed cyclic constitutive model is implemented in a finite-element software with the ability of programming and then it is verified by comparing the predicted numerical responses with the behavior measured in reliable experiments. As a result, this model has the capability of predicting the main characteristics of hysteresis curves such as stiffness and strength degradation, residual relative displacements at zero stress, crack closing and reopening and energy dissipation. Hence, it can be implemented in macro-modeling simulation of masonry structures under both monotonic and cyclic loading. Keywords: Masonry, in-plane behavior, macro-modeling, hysteresis curve, finite element method