A superconducting magnet includes: a superconducting coil; a coolant container; a radiation shield; a vacuum container; a refrigerator; a current lead; a first pipe including a mounting opening in which the refrigerator is inserted and fixed; a second pipe including a lead-out opening through which the current lead passes to be led out; and a flow rate ratio maintaining mechanism connected to at least one of the downstream side of the mounting opening of the first pipe and the downstream side of the lead-out opening of the second pipe, the flow rate ratio maintaining mechanism allowing the vaporized coolant to flow through the first pipe and the second pipe at a constant flow rate ratio.