PURPOSE: To prevent loosening of a rope etc. from occurring by providing a movable weight between a floating pier main body on the sea and a fixed weight on the bottom of the sea, and passing a rope etc. extending from the fixed weight alternately on grooved pulleys provided on the main body and the movable weight.

CONSTITUTION: A bendable continuous member 27 such as a rope, fixing both ends thereof to the fixed weight 19 is alternately passed on a grooved pulley 25 provided to the upper surface of a movable weight 23 and a grooved pulley 17 on the lower surface of the main body 10, and the continuous member 27 is always extended. After that, the main body 10 rises at high tide to raise the movable weight 23, and the main body 10 lowers at low tide to lower the movable weight 23. When the floating pier is to be moved, the movable weight 23 is fixed to the fixed weight 19 at low tide. Air is supplied while discharging water from the main body 10 to float the whole body, and it is towed by another ship. According to the constitution, the main body is always kept in a required position, and it can be easily moved.