Monte Carlo simulation was performed for the characterization of transition phenomena involved in a nonchiral molecular system exhibiting the ferroelectricity. In this system, each molecule is consisted of a combination of rigid and flexible moieties. In the simulation, a quasi-lattice model was used in which molecules move in one direction only. The driving force for the spontaneous polar ordering of molecules was assumed to arise from the tendency of chemically distinct moieties to segregate. Two transitions have been identified and their nature was characterized through the use of temperature behavior of energy, heat capacity, smectic order parameters, polarity order parameter, and fluctuations of the order parameters, and so on. As a result, the transition that occurred at a lower temperature was due to the polar to nonpolar transition, while the transition at a higher temperature was found to be the smectic to nematic transition.