An electric current sensor having a housing, magnetic circuit with a magnetic core, and a magnetic field detector with a detection cell, positioned in an air gap between ends of the core. The core is made of a non-laminated magnetic material, and the magnetic circuit has a strap made of non-magnetic material welded to the core at each side of the air gap. The magnetic field detector has a support plate on which the detection cell is mounted. The plate has a recess, opposition the detection cell, which houses one end of the magnetic circuit.