An electronic musical instrument which has a fallboard unit whose dimension in the longitudinal direction of the instrument is not increased even when the fallboard unit contains a functional component part including electrical wiring. A cover unit has a front cover and a rear cover disposed such that they are arranged in forward and rearward directions when the cover unit is closed. A hinge device pivotally connects the front cover and the rear cover such that the cover unit lays open upward a keyboard when it is open with the front cover and the rear cover being folded. An instrument body accommodates the keyboard and a musical tone generator, and includes a pivotal support member fixed therein, left and right lateral side panels, and a topboard. A guide mechanism is provided on the left and right lateral side panels, and supports the rear cover such that the rear cover is movable in the forward and rearward directions. A lower part of the rear end of the front cover below the hingedevice is pivotally supported by the pivotal support member. The topboard is below the front end of the front cover when the front cover is open.