A proximity detection device has transmitting and receiving electrodes and a multiline driving unit that simultaneously applies periodic alternating voltages to at least two of the transmitting electrodes. A measurement unit measures currents or amounts of accumulated charge from the receiving electrodes in synchronization with the simultaneous application of periodic alternating voltages to the at least two transmitting electrodes by the multiline driving unit. A linear computing unit performs linear computation of measurement results from a measurement unit in response to electrostatic capacitances of respective intersections between the transmitting and receiving electrodes. The linear computing unit has a memory unit that stores an output of the linear computation for readout at plural times. A proximity computing unit performs a computation to determine an approach and/or a position of an object relative to a detection area based on the output from the linear computing unit stored in the memory unit.