Molecular dynamics (MD) simulations are very important to study physical properties of the atoms and molecules. However, a huge amount of processing time is required to simulate a few nano-seconds of an actual experiment. Although the hardware acceleration using FPGAs provides promising results, huge design time and hardware design skills are required to implement an accelerator successfully. In this paper, we propose an FPGA accelerator designed using C-based OpenCL. We achieved over 4.6 times of speed-up compared to CPU-based processing, by using only 36% of the Stratix V FPGA resources. Maximum of 18.4 times speed-up is possible by using 80% of the FPGA resources.