A new particle acceleration method using pulsed induction cells was introduced in the super-bunch project at KEK. Unlike conventional RF acceleration, this acceleration method separates functions of acceleration and confinement. As a result, this acceleration method is capable of accelerating a very long bunch of beam or a wide mass range of particles. However, it is necessary to give a very fast pulsed- excitation to the magnetic material to induce an electric field to accelerate particles. Switching power supplies of high voltage output with very fast pulse-operation is one of the most important key technologies for this new acceleration method. Features of switching power supply developed for induction synchrotron is reported. The 31 kW MOSFET switch performed 1 MHz continuous operation with 15 nsec rise time.