A magnetic field generating-apparatus (1, 1A) for biostimulation comprising: a core (2, 22) formed by magnetic material; and coils (3, 23) wound around portions of the core (2, 22), wherein the core (2, 22) includes at least two pairs of leg portions (20b, 21b, 22b) which are juxtaposed each other, in which for the respective two pairs of leg portions (20b, 21b, 22b), there are provided gap-portions (20c, 21c) which mutually cross each other, the coils (3, 23) include first coil portions and second coil portions forming a first magnetic-path and a second magnetic-path between the two pairs of leg portions (20b, 21b, 22b) and the gap-portions (20c, 21c) respectively; and wherein depending on the first coil portions and one pair of leg portions (20b, 21b, 22b), there is generated a magnetic field of first direction which lies on the first magnetic-path, depending on the second coil portions and the other pair of leg portions (20b, 21b, 22b), there is generated a magnetic field of second direction which lies on the second magnetic-path, and depending on a magnetic field formed by synthesizing the magnetic field of first direction and the magnetic field of second direction, a living body is stimulated, the core includes a first and a second core unit (20, 21) having respective connecting portions (20a, 21a) which connect the leg portions (20b, 21b) of the respective pairs mutually, the first and the second core unit (20, 21) are differently sized and U-shaped, the mutual connecting portions (20a, 21a) for the two pairs of leg portions (20b, 21b) are arranged at twisted positions, and the end surfaces of the two pairs of leg portions (20b, 21b) lie on the same plane, or the core includes a plate-shaped base unit which connects the leg portions mutually, and the two pairs of leg portions are extending upward from the common plate-shaped base unit, and the end surfaces of the leg portions lie on the same plane. a core (2, 22) formed by magnetic material; and coils (3, 23) wound around portions of the core (2, 22), wherein the core (2, 22) includes at least two pairs of leg portions (20b, 21b, 22b) which are juxtaposed each other, in which for the respective two pairs of leg portions (20b, 21b, 22b), there are provided gap-portions (20c, 21c) which mutually cross each other, the coils (3, 23) include first coil portions and second coil portions forming a first magnetic-path and a second magnetic-path between the two pairs of leg portions (20b, 21b, 22b) and the gap-portions (20c, 21c) respectively; and wherein depending on the first coil portions and one pair of leg portions (20b, 21b, 22b), there is generated a magnetic field of first direction which lies on the first magnetic-path, depending on the second coil portions and the other pair of leg portions (20b, 21b, 22b), there is generated a magnetic field of second direction which lies on the second magnetic-path, and depending on a magnetic field formed by synthesizing the magnetic field of first direction and the magnetic field of second direction, a living body is stimulated, the core includes a first and a second core unit (20, 21) having respective connecting portions (20a, 21a) which connect the leg portions (20b, 21b) of the respective pairs mutually, the first and the second core unit (20, 21) are differently sized and U-shaped, the mutual connecting portions (20a, 21a) for the two pairs of leg portions (20b, 21b) are arranged at twisted positions, and the end surfaces of the two pairs of leg portions (20b, 21b) lie on the same plane, or the core includes a plate-shaped base unit which connects the leg portions mutually, and the two pairs of leg portions are extending upward from the common plate-shaped base unit, and the end surfaces of the leg portions lie on the same plane.