A superconducting magnet includes a superconducting coil, a refrigerant container, a radiation shield, a vacuum container, a refrigerating machine cooling an interior of the refrigerant container, a tubular current lead passing from outside of the vacuum container to inside of the refrigerant container electrically connected to the superconducting coil, a power source electrically connected to the current lead, a manometer measuring a pressure inside of the refrigerant container, a thermometer to measure a temperature of the current lead, and a control unit connected to each of the power source, the manometer, and the thermometer. The control unit raises an output of the power source to vary a value of a current flowing into superconducting coil only when a measurement value of the manometer is higher than or equal to a set value and a measurement value of the thermometer is lower than or equal to a set value.
