A hydraulic pressure spring includes a hollow cylindrical cylinder having a threaded portion at one end thereof; a closure means which is threadedly engaged with the threaded portion at the one end of the cylinder and closes the one end of the cylinder; a closure means which is provided at the other end of the cylinder and closes the other end of the cylinder; a compressible liquid which is sealed in an interior of the cylinder and is pressurized to a predetermined pressure; a rod which is passed through the closure means movably in an axial direction A and causes the liquid in the interior of the cylinder to undergo a pressure rise as the rod enters the interior of the cylinder; and a piston disposed in the interior of the cylinder and attached to one end of the rod.