An electronic keyboard musical instrument which is placed on a supporting surface when it is used, includes an instrument main unit which includes a keyboard having a plurality of keys and which generates electrical signals in response to depressions of the keys, a speaker which has a front side and a rear side and which produces sounds corresponding to the electrical signals from the instrument main unit, and an instrument main unit supporting member which is placed on the supporting surface. The instrument main unit supporting member includes an outer surface facing an external space, an internal space surrounded by the outer surface and housing the instrument main unit at a position apart upward from the supporting surface, and an opening formed in the outer surface and communicating the internal space with the external space. The speaker is attached to the outer surface with the front side facing the opening.