An autonomous hydraulic expansion and contraction apparatus comprising: a fixing unit having a fixing support member formed at an end of a lower part thereof; a cylinder unit mounted to an upper part of the fixing unit, the cylinder unit being provided therein with a receiving space for storing oil; a support unit, one side of which is inserted and mounted into the receiving space in the cylinder unit and the other side of which is located outside the cylinder unit, an expansion and contraction fixing member being mounted to an end of the other side of the support unit, the support unit being configured to move upward or downward in response to movement of the oil stored in the receiving space; a piston unit comprising a barrier type sealing part mounted to an end of the support unit, which is inserted into the receiving space, the barrier type sealing part being configured to move in response to movement of the support unit; a valve unit disposed at an outer surface of the cylinder unit, the valve unit being provided at upper and lower parts thereof with upper and lower connection members (610, 620), which communicate with the cylinder unit, a vertical connection member being mounted to ends of the upper and lower connection members (610, 620), a valve having a valve mounting hole for allowing or interrupting communication between the lower connection member and the vertical connection member in response to manipulation of a lever being mounted in a connection portion of the connection members (620, 630); and oil supply parts mounted to the ends of the upper and lower connection members (610, 620) for supplying oil into the cylinder unit, wherein the upper and lower connection members (610, 620) are coupled to the cylinder unit through cylinder coupling holes, characterized by each of the cylinder coupling holes having an inclined guide surface and an inclined support surface for allowing the smooth movement of oil and preventing concentration of a load during the movement of the oil, the inclined guide surface and the inclined support surface having different angles of inclination. a fixing unit having a fixing support member formed at an end of a lower part thereof; a cylinder unit mounted to an upper part of the fixing unit, the cylinder unit being provided therein with a receiving space for storing oil; a support unit, one side of which is inserted and mounted into the receiving space in the cylinder unit and the other side of which is located outside the cylinder unit, an expansion and contraction fixing member being mounted to an end of the other side of the support unit, the support unit being configured to move upward or downward in response to movement of the oil stored in the receiving space; a piston unit comprising a barrier type sealing part mounted to an end of the support unit, which is inserted into the receiving space, the barrier type sealing part being configured to move in response to movement of the support unit; a valve unit disposed at an outer surface of the cylinder unit, the valve unit being provided at upper and lower parts thereof with upper and lower connection members (610, 620), which communicate with the cylinder unit, a vertical connection member being mounted to ends of the upper and lower connection members (610, 620), a valve having a valve mounting hole for allowing or interrupting communication between the lower connection member and the vertical connection member in response to manipulation of a lever being mounted in a connection portion of the connection members (620, 630); and oil supply parts mounted to the ends of the upper and lower connection members (610, 620) for supplying oil into the cylinder unit, wherein the upper and lower connection members (610, 620) are coupled to the cylinder unit through cylinder coupling holes, characterized by each of the cylinder coupling holes having an inclined guide surface and an inclined support surface for allowing the smooth movement of oil and preventing concentration of a load during the movement of the oil, the inclined guide surface and the inclined support surface having different angles of inclination.