An input device for inputting information according to a state of approach of an object to a detection surface, the input device comprising: a sensor unit configured to detect a degree of approach of the object at a plurality of positions of the detection surface; a sensor control unit configured to control the sensor unit so that the sensor unit performs a periodic detection operation of detecting a degree of approach of the object at the plurality of positions in each cycle; a coordinate/degree-of-approach data generation unit configured to generate coordinate data indicating coordinates of a position of the same object approaching the detection surface and degree-of-approach data indicating the degree of approach at the coordinates over a plurality of cycles of the detection operation on the basis of a result of the detection of the sensor unit in each cycle of the detection operation; a noise detection unit configured to detect noise included in a result of the detection of the sensor unit; an approach determination unit configured to compare the degree-of-approach data of each object with a threshold value in each cycle of the detection operation, and determine, for each object, whether the object approaches the detection surface on the basis of a result of the comparison; and a threshold value adjustment unit configured to adjust the threshold value, characterized in that the noise detection unit is configured to acquire, from the sensor unit, detection data obtained continuously a plurality of times at the same detection position and the noise detection unit specifies a maximum value and a minimum value among the plurality of detection data obtained through the plurality of detections, and obtains a value obtained by subtracting the minimum value from the maximum value as the level of noise detected in the noise detection unit, the threshold value adjustment unit adjusts the threshold value according to the level of noise detected in the noise detection unit and according to the number of objects determined to approach the detection surface in the approach determination unit. a sensor unit configured to detect a degree of approach of the object at a plurality of positions of the detection surface; a sensor control unit configured to control the sensor unit so that the sensor unit performs a periodic detection operation of detecting a degree of approach of the object at the plurality of positions in each cycle; a coordinate/degree-of-approach data generation unit configured to generate coordinate data indicating coordinates of a position of the same object approaching the detection surface and degree-of-approach data indicating the degree of approach at the coordinates over a plurality of cycles of the detection operation on the basis of a result of the detection of the sensor unit in each cycle of the detection operation; a noise detection unit configured to detect noise included in a result of the detection of the sensor unit; an approach determination unit configured to compare the degree-of-approach data of each object with a threshold value in each cycle of the detection operation, and determine, for each object, whether the object approaches the detection surface on the basis of a result of the comparison; and a threshold value adjustment unit configured to adjust the threshold value, characterized in that the noise detection unit is configured to acquire, from the sensor unit, detection data obtained continuously a plurality of times at the same detection position and the noise detection unit specifies a maximum value and a minimum value among the plurality of detection data obtained through the plurality of detections, and obtains a value obtained by subtracting the minimum value from the maximum value as the level of noise detected in the noise detection unit, the threshold value adjustment unit adjusts the threshold value according to the level of noise detected in the noise detection unit and according to the number of objects determined to approach the detection surface in the approach determination unit.