To develop basic technologies for the maritime transport of hydrogen energy, a liquid hydrogen experiment facility (LHEF) with system enabling observation under horizontal vibration has been designed and constructed. The LHEF consists of a liquid hydrogen optical cryostat, a gas-handling system, vacuum pumps, and apparatus for generating horizontal vibrations. The liquid hydrogen optical cryostat, which is 1200 mm in height and 300 mm in diameter, includes a vacuum jacket, a liquid nitrogen space (10.0 liters), a liquid hydrogen space (13.6 liters), a sample space (3.8 liters), optical windows, and a needle valve. The results of performance tests show that the heat leak in the liquid hydrogen space is sufficiently small. Using the LHEF under horizontal vibration, the damped oscillation of the liquid hydrogen surface is successfully observed and analyzed on the basis of a simple model.