The invention provides a force detector in which power consumption is suppressed. Four electrodes (E11-E14) are formed on a substrate (40), and an elastic deformable body (20) formed of a rubber film is disposed thereon. A conductive coating is applied on the lower surface of the elastic deformable body (20) to provide a displacing conductive layer(26). Four capacitance elements (C11-C14) are comprised by the electrodes (E11-E14) and the displacing conductive layer (26) opposed to the electrodes. The capacitance values thereof are converted into voltage values (V11-V14) by C/V converter circuit (50), and based on operation by signal processing circuit (60), an external force applied to the elastic deformable body is detected. A pair of contacting electrodes (E15, E16) are formed on the substrate (40), and when an external force with a predetermined strength or more is applied, the elastic deformable body (20) deforms, and the displacing conductive layer (26) comes into contact with both the contacting electrodes (E15, E16), simultaneously. The potential of the contacting electrode (E16) is taken-in from the terminal (T5), and when said potential is Vcc, the C/V converter circuit (50) is operated in a standby mode with less power consumption, and when said potential is GND, the circuit is operated in a normal mode.