A speed detecting apparatus for a keyboard musical instrument is provided for accurately detecting the speed of bivotal movements of a hammer and a key even if a shutter implies errors in its attachment, without affected by such errors. The speed detecting apparatus for a keyboard musical instrument comprises a pivotable key, a hammer pivotably supported by a fulcrum and configured to pivotally move in association with a pivotal movement of the key, a shutter integrally attached to the hammer, a plurality of detectors, each having a light emitter and a light receiver for receiving light emitted from the light emitter, arranged on one and the other sides of the pivotal movement path of the shutter, and a CPU for detecting a pivot speed of the hammer in response to timings at which the shutter opens and closes the light paths of the light of the plurality of detectors when the hammer pivotally moves. The plurality of detectors have detection points on respective light paths of the light from the light emitters, and are arranged such that the detection points are positioned on an arc centered at the fulcrum of the hammer.