To make a displacement characteristic graph of a measurement object very approximate to the actual displacement characteristic preparable by plotting plural coordinate points set by a coordinate point setting means and brake points set by a break point setting means in a two-dimensional coordinate space.

An automatic displacement measuring device 10 includes a laser displacement sensor LS 11 disposed near a valve element 2b of an ICV (intercept valve). The laser displacement sensor 11 radiates laser light toward a slide part of the valve element 2b by a laser light output part, and detects its reflected light by a detecting part to measure the displacement of the valve element 2b which is a slide part from the detection signal. The automatic displacement measuring device 10 further includes a data processing unit 12 for conducting data processing according to the displacement measured by the LS11 to thereby automatically obtain the operational characteristic (displacement characteristic of the valve element 2b) of the ICV 2, and create and display a graph showing the obtained operational characteristic of the ICV 2.