An object detection sensor wherein a detection electrode (electrode connected with a detection circuit via a conductor) is not exposed from a surface and an input signal is scarcely reduced when a contact area is small, which is capable of reliably detecting a contact thereof with an object in a manner substantially the same as that in the case of a large contact area even when the contact area is small is provided. The object detection sensor is provided with a sensor case made from an insulating material, a detection electrode (electrode A) disposed on an inner surface of the sensor case, a touch electrode (touch electrode A) disposed at a position opposed to the detection electrode on an outer surface of the sensor case and capacitance-coupled to the detection electrode, and a detection circuit which is connected to the detection electrode and detects a contact of an object with the touch electrode based on a change in electrostatic capacitance between the detection electrode and the ground to output a detection signal.