The critical behavior of La_0.75Ca_0.05Na_0.20MnO₃ was studied at around room temperature via magnetization measurements. From the relative slope, we deduced that the Tricritical Mean-Field model was the most suitable model. The estimated critical exponents were found to be β = 0.24 ± 0.004, γ = 0.98 ± 0.065 and δ = 5.08 at T_C = 300 K. These critical exponents satisfied the Widom scaling relation δ = 1 + γ/β, implying the reliability of our values. Based on the critical exponents, the magnetization–field–temperature (M–μ₀H–T) data around T_C collapsed into two curves, obeying the single scaling equation with ε = (T − T_C)/T_C being the reduced temperature. These results suggest short-range interaction in our sample.