A keyboard musical instrument includes a string-striking mechanism (hammer), driver, sound receiver, analyzer, and adjuster. The hammer strikes a string responsive to a change in position of an associated key of keyboard. The driver drives the hammer under a driving condition in accordance with control data. The sound receiver generates an audio signal corresponding to a sound occurring in the vicinity of the hammer. The analyzer detects the hammer striking a string by analyzing the audio signal generated when the hammer operates. The adjuster adjusts the control data in accordance with results of the analysis. The analyzer detects hammer striking a string in accordance with an intensity of the audio signal occurring within a search range, which has a predetermined relationship along a time axis with regard to a time at which the hammer commences operation.