Abstract: In response to an operation of a key, a drive signal indicating a sound waveform corresponding to the key is supplied to an excitation unit provided on a soundboard. The soundboard is vibrated in response to a mechanical vibration generated by the excitation unit and generates an actively-vibrated-soundboard sound as well as an acoustic effect generated by propagation of the vibration of the soundboard to a string. The excitation unit has a voice coil excited by the drive signal. The length of the voice coil is equal to or smaller than a sum of a magnetic path width (mw) of a magnetic path space and a double of a maximum deflection amount (sw) of the vibration member connected to the soundboard. In this way, an effective drive force for exciting the soundboard can be obtained and an enhanced responsiveness in a high frequency band can be obtained.