Operation state detecting apparatus, operation state detecting sheet, and electronic instrument

An operation state detecting apparatus includes the following. An electronic device includes an operation surface and can detect whether there is contact in a plurality of positions. A sheet material can be attached to and detached from the operation surface. The sheet material includes a projecting portion which deforms to change a contact state on the operation surface according to strength of external force. A processor of the electronic device detects whether there is contact in a plurality of positions in an individual detecting region on the operation surface on which a contact state changes by the projecting portion deforming in a state with the sheet material attached to the operation surface. The processor performs a specific process according to strength or speed of an operation applied to the projecting portion judged based on a detected result of whether contact is detected in the plurality of positions.