This paper deals with evaluation of nonlinear vibration specific characteristic of a continuous body with a gap under stationary random waves by experiments and simulations. The experimental model is a fixed beam with both ends which has mass on the center of the beam, and a thin fixed plate with both ends with a gap between the mass and the plate in a frame to fix the beam. The shapes of the transfer functions by the simulations have tendencies to be like that by the experiments. The rms values of the response acceleration and the values of the maximum response displacements by the simulations are mostly in agreement with the results of the oxperiments in the plate thickness 0.5, 0.6, and 0.8 mm. The dominant frequencies by the simulations have tendency to be larger than the experiments. The probability density for the peak magnitude of the displacements by the simulations are mostly in agreement with the results of the experiments.