Electronic keyboard musical instrument

An electronic keyboard musical instrument, including: a key; a mass body driven by a depressed key for pivotally moving in a movement region between a rest position and an end position; a back check portion to back check the mass body; a position detecting portion to detect a position of the mass body; and a controller for controlling silencing of a tone, such that the currently generated tone is silenced when the mass body reaches a preset tone silencing position in its movement from the end position to the rest position, wherein the controller is configured to change the tone silencing position on the basis of respective times required for the mass body to pass through first and second sub regions of the movement region in the movement of the mass body, the second sub region being located nearer to the rest position than the first sub region.