The Ising model is a mathematical model introduced as a simplified representation of ferromagnetism in statistical physics and, as such, is concerned with the physics of phase transitions. The model consists of variables with discrete values ±1 that represent magnetic dipole moments of atoms - spins. The model assumes that each spin has only nearestneighbour interaction. Phase transition in the one-dimensional Ising model does not occur except at absolute zero temperature. Landau’s theory of phase transitions leads to the conclusion that in the two-dimensional Ising model, a phase transition of the second order occurs during the system’s transition from the ferromagnetic to the paramagnetic phase. Monte Carlo simulation generates a square lattice of the two-dimensional Ising model and calculates the thermodynamic quantities of average energy, magnetization and heat capacity, the interpretation of which leads to a conclusion about the occurrence and type of phase transition.