MAGNETIC FIELD GENERATING DEVICE

Provided is a magnetic field generating apparatus including a compressor (21), a condenser (22), an expansion valve (23), and an evaporator, which are connected in such a manner as to circulate a cooling fluid therethrough. The evaporator includes a coil (16) formed by being wound into a solenoid, the coil (16) having a plurality of microholes (32) where the cooling fluid flows, the coil (16) is connected to a resonant circuit (15) having a capacitor (33) that causes the coil (16) to resonate, and the coil (16) and the capacitor (33) are cooled with the cooling fluid. Consequently, in the magnetic field generating apparatus, excellent cooling that maintains the capacitor (33) at a constant temperature allows obtaining the stable behavior of a switching element (30) and stably generating a strong magnetic field over a long period of time.