Data input device for electronic instrument and method of entering data

A data input device includes: an operation section including an electrostatic capacitance type touch sensor; and a control circuit section which determines if a data input operation is true or false and sends an output data corresponding to a sensed data only when the data input operation is determined as true. When one or more of the sensed data are entered into the control circuit section, a coordinate is identified which determines the data input operation as true based on invalidation determination region information previously prepared for each of coordinates corresponding to the sensed data, wherein while the sensed data for the coordinate indentified is entered, the data input operation, which is implemented to a coordinate other than the identified coordinate to determine the data input operation as true among a group aggregate of the coordinates corresponding to the sensed data within an invalidation determination region, is determined as false.