a proximity detector including a pair of antennae disposed at the front edge of a door with a space ; and voltage converters for converting earth electrostatic capacities of the antennae to the corresponding voltages . the proximity detector further includes a first detecting circuit for detecting a differential signal of the outputs of the voltage converters ; and a second detecting circuit for detecting a summing signal of the outputs of the voltage converters . the movement of the door is controlled by the output of the first detecting circuit and / or the output of the second detecting circuit .