PURPOSE: To give natural oscillation to a boat for increasing the feeling of attendance received by sightseeing tourists.

CONSTITUTION: A boat 10 is moored above an oscillation machine 18 by a mooring mechanism 32 provided in a waterway 12. The oscillation machine 18 comprises three air cylinders 22, 24 disposed to form an equilateral triangle or isosceles triangle, and an oscillation plate 20 connected to these cylinders 22, 24. Each cylinder 22, 24 is connected through a valve device 52, 54 controlled by a control device 38 to an air pressure source 50. The control device 38 controls opening/closing and opening/closing quantity of the valve devices 52, 54 to expand/contract the three cylinders 22, 24 for oscillating the oscillation plate 20 in a desired direction, thereby water is lifted to give oscillation such as rolling and pitching to the boat 10.