In this work, the heavy metal ion adsorption behavior of activated carbon fibers (ACFs) containing chelating functional groups were studied. The ACFs were modified by fluorination and glycidyl methacrylate (GMA) graft polymerization in order to introduce chelating functional groups, such as iminodiacetate (IDA) groups, on the carbon surfaces. Fourier transform-infrared spectrometry (FT-IR) and X-ray photoelectron spectroscopy (XPS) were used for the analysis of surface properties of the ACFs. Specific surface area was calculated from Brunauer-Emmett-Teller (BET) equation for $N_{2}$ adsorption at 77 K. In the result of XPS, the relative intensity of oxygen peaks increased with increasing treatment times of fluorination, indicating that surface oxidation occurred due to the increased treatment time of fluorination, in spite of decrease in specific surface area by pore blocking. However, the adsorption of the heavy metal ion significantly increased with increasing treatment time of fluorination. It was understood that the IDA groups of the fluorinated ACF surfaces were introduced by GMA graft polymerization and the IDA groups led to an increase in the adsorption of heavy metal ions.