PURPOSE: To control the temp. in an imaging space, by arranging an air control device composed of a pipe having heat absorbing fins in an inclined magnetic field coil.

CONSTITUTION: An air control apparatus composed of a pipe having heat absorbing fins 22 is mounted to an inclined magnetic field coil for controlling the temp. in an imaging space. A fluid is allowed to flow through the pipe 21 to control the temp. of the fins 22 and, as a result, the temp. in the inclined magnetic field coil containing the pipe 21, that is, in the imaging space is controlled.