A magnetic resonance imaging apparatus according to an embodiment includes a gradient magnetic field power supply configured to supply power to a gradient coil. The gradient magnetic field power supply includes a plurality of switching circuits and a processing circuitry. Each of the switching circuits is configured to output a predetermined pulse voltage. The processing circuitry is configured to change the number of switching circuits to be caused to perform switching operation among the switching circuits, in accordance with an intensity of the voltage to be output to the gradient coil.