A magnetic field generating-apparatus (1) for biostimulation including: a C-shaped annular core (2,22) having a gap-portion (G)； and coils (3) wound around the core (2,22), wherein the core (2,22) includes a pair of facing extended-portions (2c,22c) which lie on the both sides of the gap-portion (G) and which face to each other by extending toward the adjacent directions, and includes a pair of opposite-side portions (2b) which are juxtaposed on the respective outsides of the pair of facing extended-portions (2b), and wherein the coils (3) are wound around the pair of opposite-side portions (2b) respectively.
