We studied an effect of pressure on the electronic state of YbIr 2Zn20under magnetic fields. The heavy fermion state at ambient pressure is found to be changed into an antiferromagnetic state at pressures larger than a critical pressure Pc≃ 5.2 GPa, where the electronic state indicates a superheavy fermion state with an order of the electronic specific specific heat coefficient γ = 20 J/(K 2·mol). The temperature dependence of the electrical resistivity shows a characteristic two-peak structure above 5.0 GPa, implying the combined phenomena between the Kondo effect and the crystalline electric field effect. At 7.6 GPa, the magnetoresistance shows a broad maximum at a critical field Hc, corresponding to a pressure-induced antiferromagnetic phase with the Néel temperature TN = 1.4 K. TN increases with further increasing pressure. © 2012 The Physical Society of Japan.