An apparatus for detecting the displacement of a movable member of an electronic musical instrument. The apparatus has superior mechanical durability compared to displacement sensors of the past and can withstand long-term use. The apparatus includes a sensor that provides a detectable electrical characteristic having a value and a spring that, when compressed upon displacement of the movable member acts with the sensor, causing the value of the electrical characteristic to change. The value of the electrical characteristic represents the amount of displacement of the movable member and is used by a controller of the electronic musical instrument.