PURPOSE: To make power generation in a stable condition by providing a float which swings up and down owing to the level difference of waves, allowing a fluid in a tube to move by the swinging motion of this float through an arm and cylinder, and thereby putting a fluid motor into operation.

CONSTITUTION: When a float 1 swings up and down owing to the level difference of waves, an arm 4 coupled with the float rotates with a stay 6 as fulcrum 6. The arm 4 presses piston rods 6c, 8c of cylinders 8, 8 coupled therewith alternately, and the fluid 9 in the cylinders 8 is allowed to move in reversals within a tube 11 which is coupled between the cylinders 8. Thereby a fluid motor 12 installed in this tube 11 is put in operation, and power generation is conducted by a generator 13.