Abstract: In a switch (50), a dimension between the first contact pin (51) and a swing lever (52) and between the second contact pin (52) and the swing lever (53) is set 5 mm. Accordingly, a detection value of the displacement sensor can be captured when a relative displacement not less than 5 mm is caused between the first and the second sliders, in other words, when the impulse or vibration caused by a contact of a probe against a workpiece is stilled, so that stable measurement is possible. In other words, the dimension of the workpiece can be accurately measured without being influenced by the impulse or the vibration caused when the probe touches the workpiece.