PURPOSE: To uniformly and stably send air to an acting space by making the inflow amt. of air constant regardless of the presence of air to an air intake port.

CONSTITUTION: An air inflow amt. adjusting mechanism is set to the air intake port formed to the outer peripheral wall of a free falling simulated experience apparatus. In this air inflow amt. adjusting mechanism, louver members 81 having a wing-shaped cross section are arranged so that each of them is supported in a shakable and revolvable manner at the position eccentric from its center of lift and energized to be shaken in the direction reverse to the shaking direction due to lift and opening the air intake port by a spring 85 and shaken in the direction reducing the opening area of the air intake port when air inflow speed is high corresponding to the change of air inflow speed.