An electromagnetic stirrer configured to control flow of molten steel inside a casting mold of a continuous casting apparatus for billet, the electromagnetic stirrer comprising a pair of electromagnetic coils (C1, C2) facing to each other and including a plurality of the casting molds at predetermined intervals in between the pair of electromagnetic coils (C1, C2), wherein: two tooth parts are provided to an iron core of each of the pair of electromagnetic coils (C1, C2) in a manner to project to a side of the casting molds; each of the two tooth parts includes an inner winding on outside thereof and the two tooth parts with the inner windings are wrapped up with an outer winding applied to outside of the inner windings; and currents A, B and C each having a phase difference of 120° to each other are applied to the inner windings and the outer winding from a power source of three-phase alternating current; wherein: when a distance L between the pair of electromagnetic coils (C1, C2) disposed in a manner to face to each other and to include the plurality of casting molds in between is 500 mm or more, current direction to be applied to the inner windings and the outer winding is, from one end side to the other end side of casting direction, for one of the pair of electromagnetic coils (C1, C2), -B, +C, -C, +A, -A, +B in the order mentioned, and for the other of the pair of electromagnetic coils (C1, C2), -B, +A, -A, +C, -C, +B in the order mentioned; when the distance L is no more than 500 mm, the current direction to be applied to the inner windings and the outer winding is, from one end side to the other end side of the casting direction, for one of the pair of electromagnetic coils (C1, C2), -B, +C, -C, +A, -A, +B and for the other of the pair of electromagnetic coils (C1, C2), +B, -A, +A, -C, +C, -B; and when the number of casting molds to be disposed to a region between an end surface of one end side and an end surface of the other end side of the casting direction of the pair of electromagnetic coils (C1, C2) is defined as n, the external size of each of the casting molds is defined as φ (mm), and the width of each of the electromagnetic coils (C1, C2) is defined as W (mm), the number of the casting molds satisfies following formula: n × φ < W. two tooth parts are provided to an iron core of each of the pair of electromagnetic coils (C1, C2) in a manner to project to a side of the casting molds; each of the two tooth parts includes an inner winding on outside thereof and the two tooth parts with the inner windings are wrapped up with an outer winding applied to outside of the inner windings; and currents A, B and C each having a phase difference of 120° to each other are applied to the inner windings and the outer winding from a power source of three-phase alternating current; when a distance L between the pair of electromagnetic coils (C1, C2) disposed in a manner to face to each other and to include the plurality of casting molds in between is 500 mm or more, current direction to be applied to the inner windings and the outer winding is, from one end side to the other end side of casting direction, for one of the pair of electromagnetic coils (C1, C2), -B, +C, -C, +A, -A, +B in the order mentioned, and for the other of the pair of electromagnetic coils (C1, C2), -B, +A, -A, +C, -C, +B in the order mentioned; when the distance L is no more than 500 mm, the current direction to be applied to the inner windings and the outer winding is, from one end side to the other end side of the casting direction, for one of the pair of electromagnetic coils (C1, C2), -B, +C, -C, +A, -A, +B and for the other of the pair of electromagnetic coils (C1, C2), +B, -A, +A, -C, +C, -B; and when the number of casting molds to be disposed to a region between an end surface of one end side and an end surface of the other end side of the casting direction of the pair of electromagnetic coils (C1, C2) is defined as n, the external size of each of the casting molds is defined as φ (mm), and the width of each of the electromagnetic coils (C1, C2) is defined as W (mm), the number of the casting molds satisfies following formula: n × φ < W.