1. A sensor for sensing a surface shape of an object surface, comprising: an input unit having a contact surface to be brought into contact with the object surface, said input unit having a plurality of electrodes arranged laterally with intervals in a first direction; and a converter for detecting degrees of an electrical resistance between pairs of adjacent of said laterally arranged electrodes of said plurality of electrodes, and forming data representing a distribution of said electrical resistance in said first direction, said electrical resistance being variable by contact of said contact surface with the object surface.