The High-Luminosity LHC is planned to start the operation in 2026 with the increased luminosity of about $5\times10^{34}\ \mathrm{cm^{-2}s^{-1}}$ in order to provide more precise measurements of the standard model processes and to extend the reach for new particles. The trigger and readout electronics for the ATLAS experiment are planned to be replaced by new ones to cope with the higher event rate at the High-Luminosity LHC. The end-cap muon trigger plans to select the events using the deflection angle between the segments before and after the magnetic field. The Thin Gap Chamber (TGC) provides the segments after the magnetic field with 3 mrad angular resolution. In order to implement the new TGC trigger, the front-end boards of TGC need to send the hit data for all channels ($\sim$320,000 channels) to the off-detector electronics. The prototype of the front-end board with the concept for the upgrade has been developed and demonstrated using muon test beam line at CERN. In this report, we introduce the prototype of the front-end board and the results of the beam test.