Abstract: In a hinge device, right-hand spiral cams formed on a lower portion of a rotational shaft are engaged with right-hand spiral guides grooves, and left-hand inclinated guide protrusions are engaged with left-hand spiral guide grooves formed on an outer circumference of an elevating pipe. When the elevating pipe moves upwardly or downwardly, the load produced by hydraulic pressure can be applied uniformly to the shaft. Therefore, it is improbable to break out or cut out the spiral cam formed on the shaft, the spiral guide grooves on the elevating pipe and the guide protrusion on the stationary pipe. As a result, the hinge device has a relatively long life-time. Also, the hinge device can reduce or prevent damage in respect of life and property.