A superconducting magnetic field generating device includes: a superconductor including an outer superconductor formed with a high temperature superconducting material in a cylindrical shape and generating a trapped magnetic field, and an inner superconductor formed with a high temperature superconducting material in a cylindrical shape and coaxially disposed with the outer superconductor on the inner circumferential side; and a cooling device cooling the outer and inner superconductors to a temperature equal to or lower than the superconducting transition temperature, wherein the inner superconductor is formed so that a ratio (Jcθ1/Jcz1) of a critical current density (Jcθ1) of the inner superconductor in the circumferential direction to a critical current density (Jcz1) of the inner superconductor in the axial direction is closer to 1 than a ratio (Jcθ2/Jcz2) of the critical current density (Jcθ2) in the circumferential direction to a critical current density (Jcz2) of the outer superconductor of the out
