There is provided an MRI system in which magnetostatic field can be stably generated by keeping the cooling capacity of a cryocooler in a proper range. The magnetic resonance imaging apparatus using a superconducting magnet (101) is equipped with a superconducting coil (201, 202), a container (203, 204) for accommodating the superconducting coil and refrigerant, a cooling unit (208) for liquefying vaporized gas of the refrigerant in the container again, a pressure detector (215) for detecting the pressure in the container, a heating unit (216) for heating in at least one of the cooling unit and the container, a controller (127) and a computer (114). The controller (127) controls the heat value of the heating unit (216) in accordance with the pressure detected by the pressure detector (215). The computer (114) judges by using the heat value of the heating unit (216) whether maintenance of the cooling unit should be performed or not.