A contactless electricity supply system comprising: a second coil (12, 22) adapted to send or receive electricity to or from a first coil (12, 22) contactlessly at least through magnetic coupling therebetween; a plurality of sensors configured to sense a positional deviation between the first coil (12, 22) and the second coil (12, 22), wherein the plurality of sensors includes a signal sending section being composed of a single signal sending antenna which is provided at the central point of the signal sending section and a signal receiving section, which is composed of a plurality of signal receiving antennas (13a, 13b, 13c, 13d), and wherein the signal sending section and the signal receiving section are arranged such that the distance between the position of each signal receiving antenna (13a, 13b, 13c, 13d) and the position of the signal sending section is equal to each other in case a central point of the first coil (12, 22) and a central point of the second coil (12, 22) are identical to each other in the direction of the coil plains; a position sensing means configured to compare output values of the plurality of signal receiving antennas (13a, 13b, 13c, 13d) with a predetermined reference value, and to sense a positional relationship between the first coil (12, 22) and the second coil (12, 22); and characterized in further comprising a foreign object detection means configured to obtain absolute values of differences among the output values of the plurality of signal receiving antennas (13a, 13b, 13c, 13d), to compare each difference with a predetermined threshold value for foreign object detection, and to detect whether or not a foreign object is present between the first coil (12, 22) and the second coil (12, 22) on a basis of a result of the comparison. a second coil (12, 22) adapted to send or receive electricity to or from a first coil (12, 22) contactlessly at least through magnetic coupling therebetween; a plurality of sensors configured to sense a positional deviation between the first coil (12, 22) and the second coil (12, 22), wherein the plurality of sensors includes a signal sending section being composed of a single signal sending antenna which is provided at the central point of the signal sending section and a signal receiving section, which is composed of a plurality of signal receiving antennas (13a, 13b, 13c, 13d), and wherein the signal sending section and the signal receiving section are arranged such that the distance between the position of each signal receiving antenna (13a, 13b, 13c, 13d) and the position of the signal sending section is equal to each other in case a central point of the first coil (12, 22) and a central point of the second coil (12, 22) are identical to each other in the direction of the coil plains; a position sensing means configured to compare output values of the plurality of signal receiving antennas (13a, 13b, 13c, 13d) with a predetermined reference value, and to sense a positional relationship between the first coil (12, 22) and the second coil (12, 22); and characterized in further comprising a foreign object detection means configured to obtain absolute values of differences among the output values of the plurality of signal receiving antennas (13a, 13b, 13c, 13d), to compare each difference with a predetermined threshold value for foreign object detection, and to detect whether or not a foreign object is present between the first coil (12, 22) and the second coil (12, 22) on a basis of a result of the comparison.