An electronic keyboard musical instrument, including: a keyboard; a musical-sound signal generating circuit; at least one speaker for emitting sound in accordance with a generated signal; a speaker accommodating body accommodating the speaker in its inner space; and at least one resonator disposed in the accommodating body, wherein the accommodating body includes a sound emission path by which the sound emitted by the speaker is introduced to an exterior of the accommodating body via the inner space for sound propagation to the exterior, a control point of the resonator is located at a position corresponding to an antinode of a sound pressure in a natural vibration mode at a specific frequency generated in the inner space by driving of the speaker, and the resonator resonates at the specific frequency for adjusting the sound pressure, whereby the sound is emitted from the sound emission path to the exterior.