We have investigated the microstructure formed in association with charge ordering transition in perovskite manganites Pr 0.55 Ca 0.45 MnO 3 (PCMO) and Nd 0.5 Sr 0.5 MnO 3 (NSMO). By optical microscope observation, surface relief is observed below the charge ordering transition temperature T CO (CO represents charge ordering phase) for both of the specimens. Two surface trace analysis and Laue back reflection technique has been revealed that microstructures are composed of twinned variants which have {101} CO and {112} CO twinning planes for PCMO and NSMO, respectively. We have also investigated the magnetic field dependence of T CO by magnetization measurements and found that the T CO decreases parabolically with increasing magnetic field. This magnetic field dependence of T CO in PCMO is in good agreement with the calculated one based on the Clausius–Clapeyron equation.