Deuterium plasma experiments are planned in Large Helical Device (LHD). During deuterium plasma discharges, 1 MeV tritons are produced by D-D fusion reactions between deuterium beams and deuterium thermal plasmas. The motions of these energetic tritons are complicated because of their large finite orbit effect and the three-dimensional magnetic field configuration of LHD. The confinement of energetic tritons is investigated by the Global NEoclassical Transport (GNET) code, which can solve the five-dimensional drift kinetic equation using Monte Carlo methods. We evaluate the velocity space distribution and particle loss fraction of the energetic tritons. The loss of the tritons is attributed to two processes: prompt orbit loss and diffusive loss. The loss fraction of energetic tritons increases to 30% on a short time scale of approximately 10−5 s by prompt orbit loss and then gradually increases to 90% on a slow-down time scale of approximately 10−1 s by diffusive loss for the assumed plasma parameters. The prompt loss fraction is also almost independent of the plasma density and largely depends on the magnetic configuration.