The frustrated system is one of main subjects in critical phenomena because of its rich phase diagrams and possibility of new universality classes. The equilibrium Monte Carlo simulation is a useful technique to study critical phenomena and has provided many helpful informations in statistical mechanics. Although it works even in frustrated systems, it sometimes suffers difficulties in the analysis due to large fluctuation and degeneracy, which restrict the available system sizes too small.In standard Monte Carlo simulations, the total amount of calculation time is consist of equilibration and averaging, and is, in usual, proportional to the equilibration time τ eq , since the averaging time is taken several times of τ eq . The equilibration from a fixed non-equilibrium state is achieved when the spin correlation ξ(t) grows up to the scale of the correlation length ξ eq in equilibrium or the system size L. In the critical regime, since ξ eq becomes larger than sizes simulated, τ eq becomes longer as L is larger. In frustrated systems, the fluctuation and degeneracy reveal a slow dynamics, that also makes τ eq very large. Therefore, available system sizes are reduced. In small systems, the correction to scaling is necessary to discuss critical phenomena accurately which makes estimations for the critical point and critical exponents complicated. The development and improvement of simulation technique in last decades have been mainly devoted to overcome such difficulties.Recently, efficient Monte Carlo technique is proposed to study critical phenomena using non-equilibrium relaxation (NER) process. 1-11) One may observe the relaxation of the order parameter (e.g., the magnetization in the ferromagnetic case) in the thermalization process from the complete ordered state. It provides the critical erature and the dynamic critical exponent accurately. This analysis has been used successfully to study various such as ferromagnetic (FM) Ising dtemp problems mo 2808 els, 2-5) XY models, 6) spin glass models 7-10) and quantum spin systems. 11) Since only the process in equilibration is observed, one can simulate quite large systems; as large as the memory permits. Recently, the method is extended to estimate various exponents using quantities of fluctuations (susceptibility, specific heat and so on). 4, 5)The critical exponents can be determined by asymptotic powers of such quantities or their combinations. The correlation length ξ(t) in the non-equilibrium process, which grows up to ξ eq , is finite transiently even at the critical point. The finite-size effect does not appear while ξ(t) L. If one may prepare systems with sizes larger than the maximum correlation length observed in the simulation, any finite-size effect is not necessary to be taken into account for the estimation of the critical point and the critical exponent. Therefore, the NER method is useful to study systems in which strong fluctuations appear or sufficient sizes can not be prepared on account of large equilibration time. It is appropriate much to st...