Disclosed is a key sheet helping to solve problems caused by a rubber-like elastic material filling dividing grooves. A key sheet (1) is provided with protrusions (3a) swelling from the back surface (2e) of an operation plate (2) toward dividing grooves (2a). The protrusions (3a), which are formed by a film sheet (3) formed of a thermoplastic resin, can prevent the problems when the rubber-like elastic material filling the dividing grooves (2a) are exposed, that is, separation or severance of the rubber-like elastic material. Further, nails or fingertips are not easily allowed to enter the dividing grooves (2a) of the operation plate (2). The protrusions (3a) in the grooves formed by the film sheet (3) are not easily worn out through repeated depressing operation, thus realizing a thin and safe key sheet (1).