Abstract: A keyboard having multiple key-switches, wherein a surface generally defined by top faces of keys of the key-switches is downwardly curved in a plane perpendicular to rows of the keys, comprising an upper casing of synthetic resin which includes a top frame portion having a rectangular aperture and side walls defining right and left sides of the aperture. The top frame portion has downward extensions extending downwardly from the side walls. The upper casing further comprises a key-holder plate portion of planar flat shape for supporting the rows of the keys perpendicular to the right and left sides of the aperture.