A system for measuring a magnetic field, comprising a magnetic field sensor, a measuring device and a wire, wherein,
- said magnetic field sensor includes
- a first conductor layer having a first loop portion which is formed in an open loop shape and which includes two ends and a gap therebetween,
- a first insulating layer which is formed on said first conductor layer and which has a hole in one end of the first loop portion,
- a second conductor layer which has a second loop portion,
- having one side crossing over the gap of the first loop portion from other end of the first loop portion to one end along a first straight line, through which one end and other end of the first loop portion are connected with each other, or in an outside of the first loop, and
- being formed in an open loop shape and having a connector electrically connecting said second conductor layer and said first conductor layer via the hole of said first insulating film,
- a second insulating layer which is formed on said second conductor layer and which has a hole in a position substantially identical with a position of the hole of said first insulating layer, and
- a third conductor layer which is formed on said second insulating layer, and which has a third loop portion
- having two ends and a gap and being formed in an open loop shape which is open in a direction substantially identical with an opening direction of said first loop portion,
- including a connector electrically connecting said third conductor layer to said second conductor layer via the hole of said second insulating layer, and
- being formed in such a way that a second straight line, through which one end and other end of said third conductor layer are connected with each other, substantially overlaps with the first straight line, and
- said magnetic field sensor
- outputting an electric signal whose magnitude is in proportion to a change rate of a magnetic field crossing over a loop, which has been formed when said first conductor layer, said second conductor layer and said third conductor layer are electrically connected with each other, and
- having characteristic impedance which is substantially identical with characteristic impedance of said measuring device and said wire,
- said measuring device measuring strength of a magnetic field based on the electric signal output by said magnetic field sensor;
- and
- said wire connecting said magnetic field sensor and said measuring device.