A fallboard structure of a keyboard instrument capable of selectively shielding or opening the inside of the instrument from or toward a player. A fallboard covers a keyboard section when it is closed, and permits the keyboard section to be operated for performance when it is open. A front plate pivotally supports the fallboard and shields a space upward and rearward of the keyboard section against a player when it is in a first state. When the fallboard is made open and engaging portions of the front plate are moved along displacement guides provided at supporting portions disposed at side portions of a keybed, the front plate is moved in unison with the fallboard and changed to a second state where the space upward and rearward of the keyboard section is open toward the player.