In this paper, the magnetization reversal of sphere-shaped ferromagnetic nanoparticles has been investigated by means of micromagnetic simulation. Some ferromagnetic particles such as Cobalt, Iron, Nickel, and Permalloy were modeled with size variation from 50 nm to 100 nm. The discretization of the ferromagnetic model used a cell size of 2.5×2.5×2.5 nm3 considering the exchange length (lex) of the materials. The quasi-static magnetic field was induced into the nano-sphere to observe the magnetization response under time dependence. It is found that the coercivity values decrease as the sphere size increased, which was confirmed the experimental results. It is also observed that the domain structure of a single particle in remanence and ground state condition are identical. Therefore, the specific understanding of magnetization process and domain structures in ferromagnetic nanoparticles could be an important step in the development of nano-patterned magnetic memory storage.