Chaotic behavior in a series resonance circuit with a ferroelectric triglycine sulfate (TGS) crystal was observed just below the ferroelectric phase transition temperature. We have analyzed the nonlinear responses by applying external electric fields to the crystal. The computer simulation was made for the modified forroelectric hysteresis loops to realize the experimental results. The fractal correlation dimension was determined to be ν=1.8 in the chaotic phase.