Large single crystals of (4-(Aminomethyl)pyridinium)2MnCl4•2H2O (1) were grown by slow evaporation of solution. The crystal structure was solved to be Pī, which belong to the central symmetric space group. But small pyroelectric current was detected, as well as a ferroelectric hysteresis loop. The pyroelectric and the ferroelectric property was attributed to the strain caused by defects. Temperature dependent magnetic curves and the M-H curve shows that 1 is antiferromagnetic ordering below 2.5 K. A field induced spin-flop is observed in the antiferromagnetic ordering state.